/// <summary> /// Creates a <see cref="ColumnDefinition"/> object representing the column passed in by <paramref name="columnList"/>. /// </summary> /// <param name="database">The database.</param> /// <param name="tableName">Name of the table.</param> /// <param name="columnList">The <see cref="JET_COLUMNLIST"/> object that represents the row in /// the temptable for this particular column.</param> /// <returns> /// A <see cref="ColumnDefinition"/> object based on the current row in the temptable /// represented by <paramref name="columnList"/>. /// </returns> internal static ColumnDefinition Load(IsamDatabase database, string tableName, JET_COLUMNLIST columnList) { lock (database.IsamSession) { using (IsamTransaction trx = new IsamTransaction(database.IsamSession)) { // load info for the column ColumnDefinition columnDefinition = new ColumnDefinition(); JET_SESID sesid = database.IsamSession.Sesid; // As of Sep 2015, JetGetColumnInfoW is only called for Win8+. Even though Unicode should have // worked in Win7, it wasn't reliable until Win8. Encoding encodingOfTextColumns = EsentVersion.SupportsWindows8Features ? Encoding.Unicode : LibraryHelpers.EncodingASCII; string columnName = Api.RetrieveColumnAsString( database.IsamSession.Sesid, columnList.tableid, columnList.columnidcolumnname, encodingOfTextColumns); JET_COLUMNBASE columnbase; Api.JetGetColumnInfo(database.IsamSession.Sesid, database.Dbid, tableName, columnName, out columnbase); columnDefinition.columnid = new Columnid(columnbase); columnDefinition.name = columnDefinition.columnid.Name; columnDefinition.type = columnDefinition.columnid.Type; ColumndefGrbit grbitColumn = (ColumndefGrbit)Api.RetrieveColumnAsUInt32(sesid, columnList.tableid, columnList.columnidgrbit).GetValueOrDefault(); columnDefinition.flags = ColumnFlagsFromGrbits(grbitColumn); columnDefinition.maxLength = Api.RetrieveColumnAsInt32(sesid, columnList.tableid, columnList.columnidcbMax).GetValueOrDefault(); columnDefinition.IsAscii = columnbase.cp == JET_CP.ASCII; byte[] defaultValueBytes = Api.RetrieveColumn(sesid, columnList.tableid, columnList.columnidDefault); Columnid isamColumnid = columnDefinition.columnid; columnDefinition.defaultValue = Converter.ObjectFromBytes( isamColumnid.Coltyp, columnDefinition.IsAscii, defaultValueBytes); columnDefinition.ReadOnly = true; return(columnDefinition); } } }
/// <summary> /// Retrieves the column. /// </summary> /// <param name="columnid">The columnid.</param> /// <param name="coltyp">The coltyp.</param> /// <param name="isAscii">Whether a textual column is Ascii.</param> /// <param name="index">The index.</param> /// <returns>The value stored within.</returns> /// <remarks> /// Itags start at 1, so we add 1 to the index /// </remarks> private object RetrieveColumn(JET_COLUMNID columnid, JET_coltyp coltyp, bool isAscii, int index) { lock (this.isamSession) { this.cursor.CheckDisposed(); if ((this.grbit & RetrieveColumnGrbit.RetrieveCopy) == 0) { this.cursor.CheckRecord(); } JET_RETINFO retinfo = new JET_RETINFO(); retinfo.ibLongValue = 0; retinfo.itagSequence = index + 1; byte[] bytes = Api.RetrieveColumn(this.isamSession.Sesid, this.tableid, columnid, this.grbit, retinfo); object obj = Converter.ObjectFromBytes(coltyp, isAscii, bytes); return(obj); } }
/// <summary> /// Creates a <see cref="ColumnDefinition"/> object representing the column passed in by <paramref name="columnBase"/>. /// </summary> /// <param name="database">The database.</param> /// <param name="tableName">Name of the table.</param> /// <param name="columnBase">The <see cref="JET_COLUMNBASE"/> object that represents this particular column.</param> /// <returns> /// A <see cref="ColumnDefinition"/> object based on the <paramref name="columnBase"/> object. /// </returns> internal static ColumnDefinition Load(IsamDatabase database, string tableName, JET_COLUMNBASE columnBase) { lock (database.IsamSession) { using (IsamTransaction trx = new IsamTransaction(database.IsamSession)) { JET_SESID sesid = database.IsamSession.Sesid; // load info for the column ColumnDefinition columnDefinition = new ColumnDefinition(); columnDefinition.columnid = new Columnid(columnBase); columnDefinition.name = columnDefinition.columnid.Name; columnDefinition.type = columnDefinition.columnid.Type; columnDefinition.flags = ColumnFlagsFromGrbits(columnBase.grbit); columnDefinition.maxLength = (int)columnBase.cbMax; columnDefinition.IsAscii = columnBase.cp == JET_CP.ASCII; // there is currently no efficient means to retrieve the // default value of a specific column from JET. so, we are // going to reach into the catalog and fetch it directly JET_TABLEID tableidCatalog; Api.JetOpenTable( sesid, database.Dbid, "MSysObjects", null, 0, OpenTableGrbit.ReadOnly, out tableidCatalog); Api.JetSetCurrentIndex(sesid, tableidCatalog, "RootObjects"); Api.MakeKey(sesid, tableidCatalog, true, MakeKeyGrbit.NewKey); Api.MakeKey( sesid, tableidCatalog, Converter.BytesFromObject(JET_coltyp.Text, true, columnBase.szBaseTableName), MakeKeyGrbit.None); Api.JetSeek(sesid, tableidCatalog, SeekGrbit.SeekEQ); JET_COLUMNBASE columnbaseCatalog; Api.JetGetTableColumnInfo(sesid, tableidCatalog, "ObjidTable", out columnbaseCatalog); uint objidTable = Api.RetrieveColumnAsUInt32(sesid, tableidCatalog, columnbaseCatalog.columnid).GetValueOrDefault(); Api.JetSetCurrentIndex(sesid, tableidCatalog, "Name"); Api.MakeKey(sesid, tableidCatalog, objidTable, MakeKeyGrbit.NewKey); Api.MakeKey(sesid, tableidCatalog, (short)2, MakeKeyGrbit.None); Api.MakeKey(sesid, tableidCatalog, columnBase.szBaseColumnName, Encoding.ASCII, MakeKeyGrbit.None); Api.JetSeek(sesid, tableidCatalog, SeekGrbit.SeekEQ); Api.JetGetTableColumnInfo(sesid, tableidCatalog, "DefaultValue", out columnbaseCatalog); byte[] defaultValueBytes = Api.RetrieveColumn(sesid, tableidCatalog, columnbaseCatalog.columnid); Columnid isamColumnid = columnDefinition.columnid; columnDefinition.defaultValue = Converter.ObjectFromBytes( isamColumnid.Coltyp, columnDefinition.IsAscii, defaultValueBytes); columnDefinition.ReadOnly = true; return(columnDefinition); } } }