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Overview
Comment:Make a hard copy of the results of a subquery lest the result of the subquery be referenced after a change to the table that generated the subquery result.
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SHA1: 9c0d80907b4dee8ee8f205c2ebdb759f5ba1d771
User & Date: drh 2015-05-18 04:24:27.963
Context
2015-05-18
12:28
Transitive constraints should only work if operands have compatible affinities and collating sequences. (check-in: 5df4056448 user: drh tags: trunk)
04:24
Make a hard copy of the results of a subquery lest the result of the subquery be referenced after a change to the table that generated the subquery result. (check-in: 9c0d80907b user: drh tags: trunk)
2015-05-16
18:31
Fix a typo in a comment. No changes to code. (check-in: ee4b74250a user: drh tags: trunk)
Changes
Unified Diff Show Whitespace Changes Patch
Changes to src/select.c.
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      sqlite3VdbeAddOp3(v, OP_Column, srcTab, i, regResult+i);
      VdbeComment((v, "%s", pEList->a[i].zName));
    }
  }else if( eDest!=SRT_Exists ){
    /* If the destination is an EXISTS(...) expression, the actual
    ** values returned by the SELECT are not required.
    */






    sqlite3ExprCodeExprList(pParse, pEList, regResult,
                  (eDest==SRT_Output||eDest==SRT_Coroutine)?SQLITE_ECEL_DUP:0);
  }

  /* If the DISTINCT keyword was present on the SELECT statement
  ** and this row has been seen before, then do not make this row
  ** part of the result.
  */
  if( hasDistinct ){








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      sqlite3VdbeAddOp3(v, OP_Column, srcTab, i, regResult+i);
      VdbeComment((v, "%s", pEList->a[i].zName));
    }
  }else if( eDest!=SRT_Exists ){
    /* If the destination is an EXISTS(...) expression, the actual
    ** values returned by the SELECT are not required.
    */
    u8 ecelFlags;
    if( eDest==SRT_Mem || eDest==SRT_Output || eDest==SRT_Coroutine ){
      ecelFlags = SQLITE_ECEL_DUP;
    }else{
      ecelFlags = 0;
    }
    sqlite3ExprCodeExprList(pParse, pEList, regResult, ecelFlags);

  }

  /* If the DISTINCT keyword was present on the SELECT statement
  ** and this row has been seen before, then do not make this row
  ** part of the result.
  */
  if( hasDistinct ){
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Changes to test/misc4.test.
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sqlite3 db :memory:
do_catchsql_test misc4-7.1 {
  CREATE TABLE t7(x);
  PRAGMA writable_schema=ON;
  UPDATE sqlite_master SET sql='CREATE TABLE [M%s%s%s%s%s%s%s%s%s%s%s%s%s';
  VACUUM;
} {1 {unrecognized token: "[M%s%s%s%s%s%s%s%s%s%s%s%s%s"}}











finish_test








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sqlite3 db :memory:
do_catchsql_test misc4-7.1 {
  CREATE TABLE t7(x);
  PRAGMA writable_schema=ON;
  UPDATE sqlite_master SET sql='CREATE TABLE [M%s%s%s%s%s%s%s%s%s%s%s%s%s';
  VACUUM;
} {1 {unrecognized token: "[M%s%s%s%s%s%s%s%s%s%s%s%s%s"}}

# 2015-05-18.  Use of ephermeral Mem content after the cursor that holds
# the canonical content has moved on.
#
do_execsql_test misc4-7.2 {
  CREATE TABLE t0(a,b);
  INSERT INTO t0 VALUES(1,0),(2,0);
  UPDATE t0 SET b=9 WHERE a AND (SELECT a FROM t0 WHERE a);
  SELECT * FROM t0 ORDER BY +a;
} {1 9 2 9}

finish_test