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Clarification and simplification and result column naming logic. 

FossilOrigin-Name: 68824a439b76a4cca05609a02de7abdc42bd1d26afbfcd047b90001c610d3c56
This commit is contained in:
drh 2017-07-12 14:10:19 +00:00
parent 47ebd4cadd
commit ec360a8d01
3 changed files with 59 additions and 28 deletions
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14
manifest
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@ -1,5 +1,5 @@
C Fix\sa\sproblem\sin\san\slsmtest\stest\scase\scaused\sby\swriting\sdata\sin\s"text"\smode\ninstead\sof\s"binary".
D 2017-07-12T14:03:13.542
C Clarification\sand\ssimplification\sand\sresult\scolumn\snaming\slogic.
D 2017-07-12T14:10:19.869
F Makefile.in 081e48dfe7f995d57ce1a88ddf4d2917b4349158648a6cd45b42beae30de3a12
F Makefile.linux-gcc 7bc79876b875010e8c8f9502eb935ca92aa3c434
F Makefile.msc 20850e3e8d4d4791e0531955852d768eb06f24138214870d543abb1a47346fba
@ -449,7 +449,7 @@ F src/printf.c 8757834f1b54dae512fb25eb1acc8e94a0d15dd2290b58f2563f65973265adb2
F src/random.c 80f5d666f23feb3e6665a6ce04c7197212a88384
F src/resolve.c 6aa1fb1212e601f65b983ee1215d69a591986c8f97a3805c425c625a53839539
F src/rowset.c 7b7e7e479212e65b723bf40128c7b36dc5afdfac
F src/select.c 6aa7e8ee53dcb9d0b77b05670bb44a1076d6747bc9b2c1f12a365b553ab6c828
F src/select.c 95659b7990e390f9bd8dc30b8975c675fcd1d46e569bc4f5a14e22a8d03e3d14
F src/shell.c 0401a716fc5343594b8ee60ce065d9a71373d3403f0b81f9fed684741e6401d1
F src/shell.c.in 98bfdeeb0808418b37f59e6d380568a76e0733efe2494377096f434b39940cad
F src/sqlite.h.in 03a422ba13da1dfef7f1aaa1ba344acf18dc867112620b1fdb2a1426cabba634
@ -1631,7 +1631,7 @@ F vsixtest/vsixtest.tcl 6a9a6ab600c25a91a7acc6293828957a386a8a93
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2
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@ -1 +1 @@
3e56a79ad8754e6da3181883154fa1c8b227a8d16c9b2a3eba925371595ae1f9
68824a439b76a4cca05609a02de7abdc42bd1d26afbfcd047b90001c610d3c56

71
src/select.c
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@ -1568,20 +1568,46 @@ static Table *tableWithCursor(SrcList *pList, int iCursor){
/*
** Generate code that will tell the VDBE the names of columns
** in the result set. This information is used to provide the
** azCol[] values in the callback.
** Compute the column names for a SELECT statement.
**
** The only guarantee that SQLite makes about column names is that if the
** column has an AS clause assigning it a name, that will be the name used.
** That is the only documented guarantee. However, countless applications
** developed over the years have made baseless assumptions about column names
** and will break if those assumptions changes. Hence, use extreme caution
** when modifying this routine to avoid breaking legacy.
**
** See Also: sqlite3ColumnsFromExprList()
**
** The PRAGMA short_column_names and PRAGMA full_column_names settings are
** deprecated. The default setting is short=ON, full=OFF. 99.9% of all
** applications should operate this way. Nevertheless, we need to support the
** other modes for legacy:
**
** short=OFF, full=OFF: Column name is the text of the expression has it
** originally appears in the SELECT statement. In
** other words, the zSpan of the result expression.
**
** short=ON, full=OFF: (This is the default setting). If the result
** refers directly to a table column, then the result
** column name is just the table column name: COLUMN.
** Otherwise use zSpan.
**
** full=ON, short=ANY: If the result refers directly to a table column,
** then the result column name with the table name
** prefix, ex: TABLE.COLUMN. Otherwise use zSpan.
*/
static void generateColumnNames(
Parse *pParse, /* Parser context */
SrcList *pTabList, /* List of tables */
SrcList *pTabList, /* The FROM clause of the SELECT */
ExprList *pEList /* Expressions defining the result set */
){
Vdbe *v = pParse->pVdbe;
int i;
Table *pTab;
sqlite3 *db = pParse->db;
int fullNames, shortNames;
int fullName; /* TABLE.COLUMN if no AS clause and is a direct table ref */
int srcName; /* COLUMN or TABLE.COLUMN if no AS clause and is direct */
#ifndef SQLITE_OMIT_EXPLAIN
/* If this is an EXPLAIN, skip this step */
@ -1594,17 +1620,19 @@ static void generateColumnNames(
assert( v!=0 );
assert( pTabList!=0 );
pParse->colNamesSet = 1;
fullNames = (db->flags & SQLITE_FullColNames)!=0;
shortNames = (db->flags & SQLITE_ShortColNames)!=0;
fullName = (db->flags & SQLITE_FullColNames)!=0;
srcName = (db->flags & SQLITE_ShortColNames)!=0 || fullName;
sqlite3VdbeSetNumCols(v, pEList->nExpr);
for(i=0; i<pEList->nExpr; i++){
Expr *p;
p = pEList->a[i].pExpr;
if( NEVER(p==0) ) continue;
Expr *p = pEList->a[i].pExpr;
assert( p!=0 );
if( pEList->a[i].zName ){
/* An AS clause always takes first priority */
char *zName = pEList->a[i].zName;
sqlite3VdbeSetColName(v, i, COLNAME_NAME, zName, SQLITE_TRANSIENT);
}else if( (p->op==TK_COLUMN || p->op==TK_AGG_COLUMN)
}else if( srcName
&& (p->op==TK_COLUMN || p->op==TK_AGG_COLUMN)
&& (pTab = tableWithCursor(pTabList, p->iTable))!=0
){
char *zCol;
@ -1616,10 +1644,7 @@ static void generateColumnNames(
}else{
zCol = pTab->aCol[iCol].zName;
}
if( !shortNames && !fullNames ){
sqlite3VdbeSetColName(v, i, COLNAME_NAME,
sqlite3DbStrDup(db, pEList->a[i].zSpan), SQLITE_DYNAMIC);
}else if( fullNames ){
if( fullName ){
char *zName = 0;
zName = sqlite3MPrintf(db, "%s.%s", pTab->zName, zCol);
sqlite3VdbeSetColName(v, i, COLNAME_NAME, zName, SQLITE_DYNAMIC);
@ -1647,6 +1672,15 @@ static void generateColumnNames(
**
** Return SQLITE_OK on success. If a memory allocation error occurs,
** store NULL in *paCol and 0 in *pnCol and return SQLITE_NOMEM.
**
** The only guarantee that SQLite makes about column names is that if the
** column has an AS clause assigning it a name, that will be the name used.
** That is the only documented guarantee. However, countless applications
** developed over the years have made baseless assumptions about column names
** and will break if those assumptions changes. Hence, use extreme caution
** when modifying this routine to avoid breaking legacy.
**
** See Also: generateColumnNames()
*/
int sqlite3ColumnsFromExprList(
Parse *pParse, /* Parsing context */
@ -1659,7 +1693,6 @@ int sqlite3ColumnsFromExprList(
u32 cnt; /* Index added to make the name unique */
Column *aCol, *pCol; /* For looping over result columns */
int nCol; /* Number of columns in the result set */
Expr *p; /* Expression for a single result column */
char *zName; /* Column name */
int nName; /* Size of name in zName[] */
Hash ht; /* Hash table of column names */
@ -1680,12 +1713,10 @@ int sqlite3ColumnsFromExprList(
for(i=0, pCol=aCol; i<nCol && !db->mallocFailed; i++, pCol++){
/* Get an appropriate name for the column
*/
p = sqlite3ExprSkipCollate(pEList->a[i].pExpr);
if( (zName = pEList->a[i].zName)!=0 ){
/* If the column contains an "AS <name>" phrase, use <name> as the name */
}else{
Expr *pColExpr = p; /* The expression that is the result column name */
Table *pTab; /* Table associated with this expression */
Expr *pColExpr = sqlite3ExprSkipCollate(pEList->a[i].pExpr);
while( pColExpr->op==TK_DOT ){
pColExpr = pColExpr->pRight;
assert( pColExpr!=0 );
@ -1693,7 +1724,7 @@ int sqlite3ColumnsFromExprList(
if( pColExpr->op==TK_COLUMN && pColExpr->pTab!=0 ){
/* For columns use the column name name */
int iCol = pColExpr->iColumn;
pTab = pColExpr->pTab;
Table *pTab = pColExpr->pTab;
if( iCol<0 ) iCol = pTab->iPKey;
zName = iCol>=0 ? pTab->aCol[iCol].zName : "rowid";
}else if( pColExpr->op==TK_ID ){