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The sqlite3ProcessJoin() routine converts a NATURAL JOIN into a JOIN USING so

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that henceforth the NATURAL keyword can be ignored.

FossilOrigin-Name: 8378e1e0d289627fb294ccd3f5865ef49df3a42b8a5aa211e21be1b42d9da753
This commit is contained in:
drh
2022-04-15 17:08:40 +00:00
parent a99e325468
commit 22c4bc8991
4 changed files with 35 additions and 29 deletions
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47
src/select.c
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@@ -320,8 +320,11 @@ int sqlite3ColumnIndex(Table *pTab, const char *zCol){
}
/*
** Search the first N tables in pSrc, from left to right, looking for a
** table that has a column named zCol.
** Search the first N tables in pSrc, looking for a
** table that has a column named zCol.
**
** Search left-to-right if bRightmost is false. Search right-to-left
** if bRightmost is true.
**
** When found, set *piTab and *piCol to the table index and column index
** of the matching column and return TRUE.
@@ -334,11 +337,15 @@ static int tableAndColumnIndex(
const char *zCol, /* Name of the column we are looking for */
int *piTab, /* Write index of pSrc->a[] here */
int *piCol, /* Write index of pSrc->a[*piTab].pTab->aCol[] here */
int bIgnoreHidden /* True to ignore hidden columns */
int bIgnoreHidden, /* True to ignore hidden columns */
int bRightmost /* Return the right-most match */
){
int i; /* For looping over tables in pSrc */
int iCol; /* Index of column matching zCol */
int rc = 0;
assert( N<=pSrc->nSrc );
assert( (piTab==0)==(piCol==0) ); /* Both or neither are NULL */
for(i=0; i<N; i++){
iCol = sqlite3ColumnIndex(pSrc->a[i].pTab, zCol);
@@ -349,10 +356,11 @@ static int tableAndColumnIndex(
*piTab = i;
*piCol = iCol;
}
return 1;
rc = 1;
if( !bRightmost ) break;
}
}
return 0;
return rc;
}
/*
@@ -509,10 +517,11 @@ static int sqlite3ProcessJoin(Parse *pParse, Select *p){
if( NEVER(pLeft->pTab==0 || pRightTab==0) ) continue;
joinType = (pRight->fg.jointype & JT_OUTER)!=0 ? EP_FromJoin : EP_InnerJoin;
/* When the NATURAL keyword is present, add WHERE clause terms for
** every column that the two tables have in common.
/* If this is a NATURAL join, synthesize an approprate USING clause
** to specify which columns should be joined.
*/
if( pRight->fg.jointype & JT_NATURAL ){
IdList *pUsing = 0;
if( pRight->fg.isUsing || pRight->u3.pOn ){
sqlite3ErrorMsg(pParse, "a NATURAL join may not have "
"an ON or USING clause", 0);
@@ -520,16 +529,20 @@ static int sqlite3ProcessJoin(Parse *pParse, Select *p){
}
for(j=0; j<pRightTab->nCol; j++){
char *zName; /* Name of column in the right table */
int iLeft; /* Matching left table */
int iLeftCol; /* Matching column in the left table */
if( IsHiddenColumn(&pRightTab->aCol[j]) ) continue;
zName = pRightTab->aCol[j].zCnName;
if( tableAndColumnIndex(pSrc, i+1, zName, &iLeft, &iLeftCol, 1) ){
addWhereTerm(pParse, pSrc, iLeft, iLeftCol, i+1, j,
joinType, &p->pWhere);
if( tableAndColumnIndex(pSrc, i+1, zName, 0, 0, 1, 0) ){
Token x;
x.z = zName;
x.n = sqlite3Strlen30(zName);
pUsing = sqlite3IdListAppend(pParse, pUsing, &x);
}
}
if( pUsing ){
pRight->fg.isUsing = 1;
pRight->u3.pUsing = pUsing;
}
}
/* Create extra terms on the WHERE clause for each column named
@@ -541,6 +554,7 @@ static int sqlite3ProcessJoin(Parse *pParse, Select *p){
*/
if( pRight->fg.isUsing ){
IdList *pList = pRight->u3.pUsing;
int bRight = (pRight->fg.jointype & JT_RIGHT)!=0;
assert( pList!=0 );
for(j=0; j<pList->nId; j++){
char *zName; /* Name of the term in the USING clause */
@@ -551,7 +565,7 @@ static int sqlite3ProcessJoin(Parse *pParse, Select *p){
zName = pList->a[j].zName;
iRightCol = sqlite3ColumnIndex(pRightTab, zName);
if( iRightCol<0
|| !tableAndColumnIndex(pSrc, i+1, zName, &iLeft, &iLeftCol, 0)
|| !tableAndColumnIndex(pSrc, i+1, zName, &iLeft, &iLeftCol,0,bRight)
){
sqlite3ErrorMsg(pParse, "cannot join using column %s - column "
"not present in both tables", zName);
@@ -5772,13 +5786,6 @@ static int selectExpander(Walker *pWalker, Select *p){
tableSeen = 1;
if( i>0 && zTName==0 ){
if( (pFrom->fg.jointype & JT_NATURAL)!=0
&& tableAndColumnIndex(pTabList, i, zName, 0, 0, 1)
){
/* In a NATURAL join, omit the join columns from the
** table to the right of the join */
continue;
}
if( pFrom->fg.isUsing
&& sqlite3IdListIndex(pFrom->u3.pUsing, zName)>=0
){