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Comment updates most. Also some small changes to the VDBE. (CVS 339)

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FossilOrigin-Name: 9b0be4fcc1cbca69f5fee906f86dfb36a323fe84
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drh
2002-01-06 17:07:40 +00:00
parent c6b52df32d
commit aacc543e23
12 changed files with 99 additions and 74 deletions
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20
src/expr.c
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@@ -12,7 +12,7 @@
** This file contains routines used for analyzing expressions and
** for generating VDBE code that evaluates expressions in SQLite.
**
** $Id: expr.c,v 1.36 2002/01/04 03:09:30 drh Exp $
** $Id: expr.c,v 1.37 2002/01/06 17:07:40 drh Exp $
*/
#include "sqliteInt.h"
@@ -49,7 +49,9 @@ static int isConstant(Expr *p){
** These operators have to be processed before column names are
** resolved because each such operator increments pParse->nTab
** to reserve cursor numbers for its own use. But pParse->nTab
** needs to be constant once we begin resolving column names.
** needs to be constant once we begin resolving column names. For
** that reason, this procedure needs to be called on every expression
** before sqliteExprResolveIds() is called on any expression.
**
** Actually, the processing of IN-SELECT is only started by this
** routine. This routine allocates a cursor number to the IN-SELECT
@@ -86,11 +88,15 @@ static int sqliteIsRowid(const char *z){
/*
** This routine walks an expression tree and resolves references to
** table columns. Nodes of the form ID.ID or ID resolve into an
** index to the table in the table list and a column offset. The opcode
** for such nodes is changed to TK_COLUMN. The iTable value is changed
** to the index of the referenced table in pTabList plus the pParse->nTab
** value. The iColumn value is changed to the index of the column of the
** referenced table.
** index to the table in the table list and a column offset. The
** Expr.opcode for such nodes is changed to TK_COLUMN. The Expr.iTable
** value is changed to the index of the referenced table in pTabList
** plus the pParse->nTab value. This value will ultimately become the
** VDBE cursor number for a cursor that is pointing into the referenced
** table. The Expr.iColumn value is changed to the index of the column
** of the referenced table. The Expr.iColumn value for the special
** ROWID column is -1. Any INTEGER PRIMARY KEY column is tried as an
** alias for ROWID.
**
** We also check for instances of the IN operator. IN comes in two
** forms: