/* ** Return a pointer corresponding to database zDb (i.e. "main", "temp") ** in connection handle pDb. If such a database cannot be found, return ** a NULL pointer and write an error message to pErrorDb. ** ** If the "temp" database is requested, it may need to be opened by this ** function. If an error occurs while doing so, return 0 and write an ** error message to pErrorDb. */ static Btree *findBtree(sqlite3 *pErrorDb, sqlite3 *pDb, const char *zDb){ int i = sqlite3FindDbName(pDb, zDb); if( i==1 ){ Parse *pParse; int rc = 0; pParse = sqlite3StackAllocZero(pErrorDb, sizeof(*pParse)); if( pParse==0 ){ sqlite3Error(pErrorDb, SQLITE_NOMEM, "out of memory"); rc = SQLITE_NOMEM; }else{ pParse->db = pDb; if( sqlite3OpenTempDatabase(pParse) ){ sqlite3ErrorClear(pParse); sqlite3Error(pErrorDb, pParse->rc, "%s", pParse->zErrMsg); rc = SQLITE_ERROR; } sqlite3StackFree(pErrorDb, pParse); } if( rc ){ return 0; } } if( i<0 ){ sqlite3Error(pErrorDb, SQLITE_ERROR, "unknown database %s", zDb); return 0; } return pDb->aDb[i].pBt; }
/* ** pE is a pointer to an expression which is a single term in the ** ORDER BY of a compound SELECT. The expression has not been ** name resolved. ** ** At the point this routine is called, we already know that the ** ORDER BY term is not an integer index into the result set. That ** case is handled by the calling routine. ** ** Attempt to match pE against result set columns in the left-most ** SELECT statement. Return the index i of the matching column, ** as an indication to the caller that it should sort by the i-th column. ** The left-most column is 1. In other words, the value returned is the ** same integer value that would be used in the SQL statement to indicate ** the column. ** ** If there is no match, return 0. Return -1 if an error occurs. */ static int resolveOrderByTermToExprList( Parse *pParse, /* Parsing context for error messages */ Select *pSelect, /* The SELECT statement with the ORDER BY clause */ Expr *pE /* The specific ORDER BY term */ ){ int i; /* Loop counter */ ExprList *pEList; /* The columns of the result set */ NameContext nc; /* Name context for resolving pE */ assert( sqlite3ExprIsInteger(pE, &i)==0 ); pEList = pSelect->pEList; /* Resolve all names in the ORDER BY term expression */ memset(&nc, 0, sizeof(nc)); nc.pParse = pParse; nc.pSrcList = pSelect->pSrc; nc.pEList = pEList; nc.allowAgg = 1; nc.nErr = 0; if( sqlite3ResolveExprNames(&nc, pE) ){ sqlite3ErrorClear(pParse); return 0; } /* Try to match the ORDER BY expression against an expression ** in the result set. Return an 1-based index of the matching ** result-set entry. */ for(i=0; i<pEList->nExpr; i++){ if( sqlite3ExprCompare(pEList->a[i].pExpr, pE) ){ return i+1; } } /* If no match, return 0. */ return 0; }