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

that henceforth the NATURAL keyword can be ignored.

FossilOrigin-Name: 8378e1e0d289627fb294ccd3f5865ef49df3a42b8a5aa211e21be1b42d9da753

manifest

@@ -1,5 +1,5 @@
-C Enhance\sthe\sIdList\sobject\sto\sexist\sin\sa\ssingle\smemory\sallocation\s(rather\sthan\na\sseparate\sallocate\sfor\sthe\sbase\sobject\sand\sthe\sarray\sof\sIDs).\s\sAlso\spermit\nan\sIdList\sobject\sto\sstore\san\sExpr\spointer\stogether\swith\seach\sname.
+C The\ssqlite3ProcessJoin()\sroutine\sconverts\sa\sNATURAL\sJOIN\sinto\sa\sJOIN\sUSING\sso\nthat\shenceforth\sthe\sNATURAL\skeyword\scan\sbe\signored.
-D 2022-04-15T15:47:14.312
+D 2022-04-15T17:08:40.527
 F .fossil-settings/empty-dirs dbb81e8fc0401ac46a1491ab34a7f2c7c0452f2f06b54ebb845d024ca8283ef1
 F .fossil-settings/ignore-glob 35175cdfcf539b2318cb04a9901442804be81cd677d8b889fcc9149c21f239ea
 F LICENSE.md df5091916dbb40e6e9686186587125e1b2ff51f022cc334e886c19a0e9982724
@@ -550,9 +550,9 @@ F src/pragma.h e690a356c18e98414d2e870ea791c1be1545a714ba623719deb63f7f226d8bb7
 F src/prepare.c fd940149c691684e7c1073c3787a7170e44852b02d1275d2e30a5b58e89cfcaf
 F src/printf.c 05d8dfd2018bc4fc3ddb8b37eb97ccef7abf985643fa1caebdcf2916ca90fa32
 F src/random.c 097dc8b31b8fba5a9aca1697aeb9fd82078ec91be734c16bffda620ced7ab83c
-F src/resolve.c 7110fc3b5a4dec5d11559141c1906c4a125349fb602f541b05db3a3d448d4b95
+F src/resolve.c 2d0f29eadbc87154399b2794490a5bfd104daf818d76e59845ab5afb9bf66824
 F src/rowset.c ba9515a922af32abe1f7d39406b9d35730ed65efab9443dc5702693b60854c92
-F src/select.c b785c8d0dc9b00d3ddac164f57d586f893c259a5ccc8c18284fec06451109278
+F src/select.c 820941d6c857e2cfdb2e56565bacd2b31b4adacc468550d44f8f9089888405e2
 F src/shell.c.in eb7f10d5e2c47bd014d92ec5db1def21fcc1ed56ffaaa4ee715b6c37c370b47f
 F src/sqlite.h.in 2a35f62185eb5e7ecc64a2f68442b538ce9be74f80f28a00abc24837edcf1c17
 F src/sqlite3.rc 5121c9e10c3964d5755191c80dd1180c122fc3a8
@@ -1947,8 +1947,8 @@ F vsixtest/vsixtest.tcl 6a9a6ab600c25a91a7acc6293828957a386a8a93
 F vsixtest/vsixtest.vcxproj.data 2ed517e100c66dc455b492e1a33350c1b20fbcdc
 F vsixtest/vsixtest.vcxproj.filters 37e51ffedcdb064aad6ff33b6148725226cd608e
 F vsixtest/vsixtest_TemporaryKey.pfx e5b1b036facdb453873e7084e1cae9102ccc67a0
-P b925f72b6f679c61b0d6be16fabe64dc7605550b7bd86f35c586dcecd8217673
+P 40f3c95871e6f40f287ef2756abafb8fc56dffdd0af69436e5c7d8e95022d94e
-R b11d83f7cd569b4ace13c0dab33f163b
+R a4dbe6f876199f457625a48f56e40a96
 U drh
-Z a062e1ee126eb5e46a77952af86658af
+Z 67a6ae70c20850bccd3ed1b730f595c0
 # Remove this line to create a well-formed Fossil manifest.

manifest.uuid

@@ -1 +1 @@
-40f3c95871e6f40f287ef2756abafb8fc56dffdd0af69436e5c7d8e95022d94e
+8378e1e0d289627fb294ccd3f5865ef49df3a42b8a5aa211e21be1b42d9da753

src/resolve.c

@@ -344,7 +344,6 @@ static int lookupName(
             ** USING clause, then skip this match.
             */
             if( cnt==1 ){
-              if( pItem->fg.jointype & JT_NATURAL ) continue;
               if( pItem->fg.isUsing
                && nameInUsingClause(pItem->u3.pUsing, zCol)
               ){

src/select.c

@@ -320,9 +320,12 @@ int sqlite3ColumnIndex(Table *pTab, const char *zCol){
 }
 
 /*
-** Search the first N tables in pSrc, from left to right, looking for a
+** 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.
 **
@@ -334,10 +337,14 @@ 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++){
@@ -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
+    /* If this is a NATURAL join, synthesize an approprate USING clause
-    ** every column that the two tables have in common.
+    ** 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) ){
+        if( tableAndColumnIndex(pSrc, i+1, zName, 0, 0, 1, 0) ){
-          addWhereTerm(pParse, pSrc, iLeft, iLeftCol, i+1, j,
+          Token x;
-                joinType, &p->pWhere);
+          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
               ){