484 lines
17 KiB
C#
484 lines
17 KiB
C#
// ---------------------------------------------------------------------------
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// <copyright file="ColumnDefinition.cs" company="Microsoft">
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// Copyright (c) Microsoft Corporation. All rights reserved.
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// </copyright>
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// ---------------------------------------------------------------------------
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// ---------------------------------------------------------------------
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// <summary>
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// </summary>
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// ---------------------------------------------------------------------
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namespace Microsoft.Database.Isam
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{
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using System;
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using System.Text;
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using Microsoft.Isam.Esent.Interop;
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using Microsoft.Isam.Esent.Interop.Server2003;
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/// <summary>
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/// A Column Definition contains the schema for a single column. It can be
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/// used to explore the schema for an existing column and to create the
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/// definition for a new column.
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/// </summary>
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public class ColumnDefinition
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{
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/// <summary>
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/// The columnid
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/// </summary>
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private Columnid columnid;
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/// <summary>
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/// The name
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/// </summary>
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private string name = null;
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/// <summary>
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/// The type
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/// </summary>
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private Type type = null;
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/// <summary>
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/// The flags
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/// </summary>
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private ColumnFlags flags = ColumnFlags.None;
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/// <summary>
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/// The maximum length
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/// </summary>
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private int maxLength = 0;
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/// <summary>
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/// The default value
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/// </summary>
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private object defaultValue = null;
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/// <summary>
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/// The read only
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/// </summary>
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private bool readOnly = false;
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/// <summary>
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/// Initializes a new instance of the <see cref="ColumnDefinition"/> class.
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/// For use when defining a new column.
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/// </summary>
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/// <param name="name">
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/// the name of the column to be defined
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/// </param>
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/// <param name="type">
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/// the type of the column to be defined
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/// </param>
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/// <param name="flags">
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/// the flags for the column to be defined
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/// </param>
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public ColumnDefinition(string name, Type type, ColumnFlags flags)
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{
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this.name = name;
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this.type = type;
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this.flags = flags;
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}
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/// <summary>
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/// Initializes a new instance of the <see cref="ColumnDefinition"/> class.
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/// For use when defining a new column.
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/// </summary>
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/// <param name="name">
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/// the name of the column to be defined
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/// </param>
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public ColumnDefinition(string name)
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{
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this.name = name;
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}
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/// <summary>
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/// Initializes a new instance of the <see cref="ColumnDefinition"/> class.
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/// </summary>
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internal ColumnDefinition()
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{
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}
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/// <summary>
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/// Initializes a new instance of the <see cref="ColumnDefinition"/> class.
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/// </summary>
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/// <param name="columnid">The columnid.</param>
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internal ColumnDefinition(Columnid columnid)
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{
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this.columnid = columnid;
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this.name = columnid.Name;
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this.type = columnid.Type;
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}
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/// <summary>
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/// Gets a value indicating whether this is a text column, whether it stores Ascii data. If false, text columns store Unicode data.
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/// </summary>
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public bool IsAscii { get; private set; }
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/// <summary>
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/// Gets the column ID of the column
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/// </summary>
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/// <remarks>
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/// The column ID is undefined if this column definition will be used
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/// to define a new column
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/// </remarks>
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public Columnid Columnid
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{
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get
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{
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return this.columnid;
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}
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}
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/// <summary>
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/// Gets the name of the column.
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/// </summary>
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public string Name
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{
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get
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{
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return this.name;
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}
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}
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/// <summary>
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/// Gets or sets the type of the column.
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/// </summary>
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public Type Type
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{
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get
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{
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return this.type;
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}
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set
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{
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this.CheckReadOnly();
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this.type = value;
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}
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}
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/// <summary>
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/// Gets or sets the column's flags.
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/// </summary>
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public ColumnFlags Flags
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{
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get
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{
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return this.flags;
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}
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set
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{
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this.CheckReadOnly();
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this.flags = value;
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}
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}
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/// <summary>
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/// Gets or sets the max length of the column in bytes.
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/// </summary>
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/// <remarks>
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/// The max length of a fixed column need not be specified when
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/// defining a new column.
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/// <para>
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/// A max length of zero for a variable length column is the same as
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/// giving that column the largest possible max length.
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/// </para>
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/// </remarks>
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public int MaxLength
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{
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get
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{
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return this.maxLength;
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}
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set
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{
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this.CheckReadOnly();
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this.maxLength = value;
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}
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}
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/// <summary>
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/// Gets or sets the default value of the column.
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/// </summary>
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/// <remarks>
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/// If the field corresponding to this column in a given record is
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/// never set then the value of that field will be the default value of
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/// the column.
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/// <para>
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/// The size of the default value is currently limited to 255 bytes
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/// by the ISAM. It is also not possible to specify a zero length
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/// default value.
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/// </para>
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/// </remarks>
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public object DefaultValue
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{
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get
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{
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return this.defaultValue;
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}
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set
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{
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this.CheckReadOnly();
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this.defaultValue = value;
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}
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}
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/// <summary>
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/// Gets a value indicating whether this column definition cannot be changed.
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/// </summary>
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public bool IsReadOnly
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{
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get
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{
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return this.readOnly;
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}
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}
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/// <summary>
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/// Sets a value indicating whether [read only].
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/// </summary>
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/// <value>
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/// <c>true</c> if [read only]; otherwise, <c>false</c>.
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/// </value>
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internal bool ReadOnly
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{
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set
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{
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this.readOnly = value;
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}
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}
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/// <summary>
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/// Returns a <see cref="System.String" /> that represents this instance.
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/// </summary>
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/// <returns>
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/// A <see cref="System.String" /> that represents this instance.
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/// </returns>
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public override string ToString()
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{
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return string.Format("ColumnDefinition({0}, {1})", this.type.Name, this.Name);
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}
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/// <summary>
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/// Creates a <see cref="ColumnDefinition"/> object representing the column passed in by <paramref name="columnList"/>.
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/// </summary>
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/// <param name="database">The database.</param>
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/// <param name="tableName">Name of the table.</param>
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/// <param name="columnList">The <see cref="JET_COLUMNLIST"/> object that represents the row in
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/// the temptable for this particular column.</param>
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/// <returns>
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/// A <see cref="ColumnDefinition"/> object based on the current row in the temptable
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/// represented by <paramref name="columnList"/>.
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/// </returns>
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internal static ColumnDefinition Load(IsamDatabase database, string tableName, JET_COLUMNLIST columnList)
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{
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lock (database.IsamSession)
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{
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using (IsamTransaction trx = new IsamTransaction(database.IsamSession))
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{
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// load info for the column
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ColumnDefinition columnDefinition = new ColumnDefinition();
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JET_SESID sesid = database.IsamSession.Sesid;
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// As of Sep 2015, JetGetColumnInfoW is only called for Win8+. Even though Unicode should have
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// worked in Win7, it wasn't reliable until Win8.
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Encoding encodingOfTextColumns = EsentVersion.SupportsWindows8Features ? Encoding.Unicode : LibraryHelpers.EncodingASCII;
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string columnName = Api.RetrieveColumnAsString(
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database.IsamSession.Sesid,
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columnList.tableid,
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columnList.columnidcolumnname,
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encodingOfTextColumns);
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JET_COLUMNBASE columnbase;
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Api.JetGetColumnInfo(database.IsamSession.Sesid, database.Dbid, tableName, columnName, out columnbase);
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columnDefinition.columnid = new Columnid(columnbase);
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columnDefinition.name = columnDefinition.columnid.Name;
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columnDefinition.type = columnDefinition.columnid.Type;
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ColumndefGrbit grbitColumn = (ColumndefGrbit)Api.RetrieveColumnAsUInt32(sesid, columnList.tableid, columnList.columnidgrbit).GetValueOrDefault();
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columnDefinition.flags = ColumnFlagsFromGrbits(grbitColumn);
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columnDefinition.maxLength = Api.RetrieveColumnAsInt32(sesid, columnList.tableid, columnList.columnidcbMax).GetValueOrDefault();
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columnDefinition.IsAscii = columnbase.cp == JET_CP.ASCII;
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byte[] defaultValueBytes = Api.RetrieveColumn(sesid, columnList.tableid, columnList.columnidDefault);
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Columnid isamColumnid = columnDefinition.columnid;
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columnDefinition.defaultValue = Converter.ObjectFromBytes(
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isamColumnid.Coltyp,
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columnDefinition.IsAscii,
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defaultValueBytes);
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columnDefinition.ReadOnly = true;
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return columnDefinition;
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}
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}
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}
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/// <summary>
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/// Creates a <see cref="ColumnDefinition"/> object representing the column passed in by <paramref name="columnBase"/>.
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/// </summary>
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/// <param name="database">The database.</param>
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/// <param name="tableName">Name of the table.</param>
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/// <param name="columnBase">The <see cref="JET_COLUMNBASE"/> object that represents this particular column.</param>
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/// <returns>
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/// A <see cref="ColumnDefinition"/> object based on the <paramref name="columnBase"/> object.
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/// </returns>
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internal static ColumnDefinition Load(IsamDatabase database, string tableName, JET_COLUMNBASE columnBase)
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{
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lock (database.IsamSession)
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{
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using (IsamTransaction trx = new IsamTransaction(database.IsamSession))
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{
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JET_SESID sesid = database.IsamSession.Sesid;
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// load info for the column
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ColumnDefinition columnDefinition = new ColumnDefinition();
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columnDefinition.columnid = new Columnid(columnBase);
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columnDefinition.name = columnDefinition.columnid.Name;
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columnDefinition.type = columnDefinition.columnid.Type;
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columnDefinition.flags = ColumnFlagsFromGrbits(columnBase.grbit);
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columnDefinition.maxLength = (int)columnBase.cbMax;
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columnDefinition.IsAscii = columnBase.cp == JET_CP.ASCII;
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// there is currently no efficient means to retrieve the
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// default value of a specific column from JET. so, we are
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// going to reach into the catalog and fetch it directly
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JET_TABLEID tableidCatalog;
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Api.JetOpenTable(
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sesid,
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database.Dbid,
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"MSysObjects",
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null,
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0,
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OpenTableGrbit.ReadOnly,
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out tableidCatalog);
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Api.JetSetCurrentIndex(sesid, tableidCatalog, "RootObjects");
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Api.MakeKey(sesid, tableidCatalog, true, MakeKeyGrbit.NewKey);
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Api.MakeKey(
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sesid,
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tableidCatalog,
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Converter.BytesFromObject(JET_coltyp.Text, true, columnBase.szBaseTableName),
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MakeKeyGrbit.None);
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Api.JetSeek(sesid, tableidCatalog, SeekGrbit.SeekEQ);
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JET_COLUMNBASE columnbaseCatalog;
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Api.JetGetTableColumnInfo(sesid, tableidCatalog, "ObjidTable", out columnbaseCatalog);
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uint objidTable = Api.RetrieveColumnAsUInt32(sesid, tableidCatalog, columnbaseCatalog.columnid).GetValueOrDefault();
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Api.JetSetCurrentIndex(sesid, tableidCatalog, "Name");
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Api.MakeKey(sesid, tableidCatalog, objidTable, MakeKeyGrbit.NewKey);
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Api.MakeKey(sesid, tableidCatalog, (short)2, MakeKeyGrbit.None);
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Api.MakeKey(sesid, tableidCatalog, columnBase.szBaseColumnName, Encoding.ASCII, MakeKeyGrbit.None);
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Api.JetSeek(sesid, tableidCatalog, SeekGrbit.SeekEQ);
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Api.JetGetTableColumnInfo(sesid, tableidCatalog, "DefaultValue", out columnbaseCatalog);
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byte[] defaultValueBytes = Api.RetrieveColumn(sesid, tableidCatalog, columnbaseCatalog.columnid);
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Columnid isamColumnid = columnDefinition.columnid;
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columnDefinition.defaultValue = Converter.ObjectFromBytes(
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isamColumnid.Coltyp,
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columnDefinition.IsAscii,
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defaultValueBytes);
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columnDefinition.ReadOnly = true;
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return columnDefinition;
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}
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}
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}
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/// <summary>
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/// Converts <see cref="ColumndefGrbit"/> to <see cref="ColumnFlags"/>.
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/// </summary>
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/// <param name="grbitColumn">The grbit to convert.</param>
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/// <returns>A <see cref="ColumnFlags"/> value equivalent to <paramref name="grbitColumn"/>.</returns>
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private static ColumnFlags ColumnFlagsFromGrbits(ColumndefGrbit grbitColumn)
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{
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ColumnFlags flags = ColumnFlags.None;
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if ((grbitColumn & ColumndefGrbit.ColumnFixed) != 0)
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{
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flags = flags | ColumnFlags.Fixed;
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}
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if ((grbitColumn & (ColumndefGrbit.ColumnFixed | ColumndefGrbit.ColumnTagged)) == 0)
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{
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flags = flags | ColumnFlags.Variable;
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}
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if ((grbitColumn & ColumndefGrbit.ColumnTagged) != 0)
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{
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flags = flags | ColumnFlags.Sparse;
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}
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if ((grbitColumn & ColumndefGrbit.ColumnNotNULL) != 0)
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{
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flags = flags | ColumnFlags.NonNull;
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}
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if ((grbitColumn & ColumndefGrbit.ColumnVersion) != 0)
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{
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flags = flags | ColumnFlags.Version;
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}
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if ((grbitColumn & ColumndefGrbit.ColumnAutoincrement) != 0)
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{
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flags = flags | ColumnFlags.AutoIncrement;
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}
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if ((grbitColumn & ColumndefGrbit.ColumnUpdatable) != 0)
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{
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flags = flags | ColumnFlags.Updatable;
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}
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if ((grbitColumn & ColumndefGrbit.ColumnMultiValued) != 0)
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{
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flags = flags | ColumnFlags.MultiValued;
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}
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if ((grbitColumn & ColumndefGrbit.ColumnEscrowUpdate) != 0)
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{
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flags = flags | ColumnFlags.EscrowUpdate;
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}
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if ((grbitColumn & ColumndefGrbit.ColumnFinalize) != 0)
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{
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flags = flags | ColumnFlags.Finalize;
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}
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if ((grbitColumn & ColumndefGrbit.ColumnUserDefinedDefault) != 0)
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{
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flags = flags | ColumnFlags.UserDefinedDefault;
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}
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if ((grbitColumn & Server2003Grbits.ColumnDeleteOnZero) != 0)
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{
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flags = flags | ColumnFlags.DeleteOnZero;
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}
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return flags;
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}
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/// <summary>
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/// Checks the read only status.
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/// </summary>
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/// <exception cref="System.NotSupportedException">this column definition cannot be changed</exception>
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private void CheckReadOnly()
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{
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if (this.readOnly)
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{
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throw new NotSupportedException("this column definition cannot be changed");
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}
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}
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}
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}
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