mirror of
https://github.com/MichaelGrafnetter/DSInternals
synced 2024-12-14 10:25:51 +00:00
209 lines
6.7 KiB
C#
209 lines
6.7 KiB
C#
// ---------------------------------------------------------------------------
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// <copyright file="Columnid.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 Microsoft.Isam.Esent.Interop;
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using Microsoft.Isam.Esent.Interop.Vista;
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/// <summary>
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/// Identifies a column in a table
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/// </summary>
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/// <remarks>
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/// A Columnid contains the name of a column and its internal identifier.
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/// A Columnid also encodes the type of the column which is used for conversions to and from CLR objects.
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/// Retrieving an column by columnid is more efficient than retrieving a column by name, as the name to
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/// columnid and type lookup can be expensive
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/// </remarks>
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public class Columnid
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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 readonly JET_COLUMNID columnid;
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/// <summary>
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/// The column type of this column.
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/// </summary>
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private readonly JET_coltyp coltyp;
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/// <summary>
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/// The name
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/// </summary>
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private readonly string name;
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/// <summary>
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/// The CLR type that closest represents the data stored in the database.
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/// </summary>
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private readonly Type type;
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/// <summary>
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/// Whether the column contains ASCII data (text columns only).
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/// </summary>
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private readonly bool isAscii;
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/// <summary>
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/// Initializes a new instance of the <see cref="Columnid"/> class.
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/// </summary>
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/// <param name="columnbase">The column identifier.</param>
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internal Columnid(JET_COLUMNBASE columnbase)
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: this(columnbase.szBaseColumnName, columnbase.columnid, columnbase.coltyp, columnbase.cp == JET_CP.ASCII)
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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="Columnid"/> class.
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/// </summary>
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/// <param name="name">The column name.</param>
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/// <param name="columnid">The column identifier.</param>
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/// <param name="coltyp">The column type.</param>
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/// <param name="isAscii">If it's a text column, whether the data is ASCII or Unicode.</param>
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internal Columnid(string name, JET_COLUMNID columnid, JET_coltyp coltyp, bool isAscii)
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{
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this.name = name;
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this.columnid = columnid;
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this.coltyp = coltyp;
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this.isAscii = isAscii;
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switch (coltyp)
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{
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case JET_coltyp.Nil:
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throw new ArgumentOutOfRangeException("columnid.Type", "Nil is not valid");
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case JET_coltyp.Bit:
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this.type = typeof(bool);
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break;
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case JET_coltyp.UnsignedByte:
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this.type = typeof(byte);
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break;
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case JET_coltyp.Short:
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this.type = typeof(short);
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break;
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case JET_coltyp.Long:
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this.type = typeof(int);
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break;
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case JET_coltyp.Currency:
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this.type = typeof(long);
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break;
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case JET_coltyp.IEEESingle:
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this.type = typeof(float);
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break;
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case JET_coltyp.IEEEDouble:
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this.type = typeof(double);
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break;
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case JET_coltyp.DateTime:
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this.type = typeof(DateTime);
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break;
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case JET_coltyp.Binary:
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this.type = typeof(byte[]);
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break;
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case JET_coltyp.Text:
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this.type = typeof(string);
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break;
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case JET_coltyp.LongBinary:
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this.type = typeof(byte[]);
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break;
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case JET_coltyp.LongText:
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this.type = typeof(string);
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break;
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case VistaColtyp.UnsignedLong:
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this.type = typeof(uint);
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break;
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case VistaColtyp.LongLong:
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this.type = typeof(long);
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break;
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case VistaColtyp.GUID:
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this.type = typeof(Guid);
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break;
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case VistaColtyp.UnsignedShort:
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this.type = typeof(ushort);
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break;
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default:
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throw new ArgumentOutOfRangeException("columnid.Coltyp", "unknown type");
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}
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}
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/// <summary>
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/// Gets a value indicating whether the column contains ASCII data (text columns only).
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/// </summary>
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public bool IsAscii
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{
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get
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{
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return this.isAscii;
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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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/// <remarks>
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/// A column name is only unique in the context of a specific table.
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/// </remarks>
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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 the type of the column.
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/// </summary>
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/// <value>
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/// The type.
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/// </value>
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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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}
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/// <summary>
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/// Gets the interop columnid.
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/// </summary>
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/// <value>
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/// The interop columnid.
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/// </value>
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internal JET_COLUMNID InteropColumnid
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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 underlying ESE <see cref="JET_coltyp"/> of the column.
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/// </summary>
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internal JET_coltyp Coltyp
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{
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get
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{
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return this.coltyp;
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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("Columnid({0}, {1}, {2}, IsAscii={3})", this.Name, this.type.Name, this.coltyp, this.isAscii);
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}
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}
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} |