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Overview
Comment:Fix handling of "DROP TABLE" commands when "PRAGMA defer_foreign_keys=1" is set.
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SHA1:27001356ed8201529b3f31d4313f2010f1b4e1b1
User & Date: dan 2013-10-12 15:12:43
Context
2013-10-12
20:22
Restore the index_list pragma back to its former operation. Create a new PRAGMA stats used to access the table and index widths and heights. check-in: f0cf8c85 user: drh tags: trunk
19:06
In "PRAGMA foreign_key_check", treat missing parent tables as empty (instead of as errors). Closed-Leaf check-in: 8c13a7fd user: dan tags: fkc-missing-parent-tables
15:12
Fix handling of "DROP TABLE" commands when "PRAGMA defer_foreign_keys=1" is set. check-in: 27001356 user: dan tags: trunk
13:16
Add tests that demonstrate that PRAGMA defer_foreign_keys will reset to off at the conclusion of the next transaction. check-in: 67e28a11 user: drh tags: trunk
Changes
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Changes to src/fkey.c.

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      /* Search for a deferred foreign key constraint for which this table
      ** is the child table. If one cannot be found, return without 
      ** generating any VDBE code. If one can be found, then jump over
      ** the entire DELETE if there are no outstanding deferred constraints
      ** when this statement is run.  */
      FKey *p;
      for(p=pTab->pFKey; p; p=p->pNextFrom){
        if( p->isDeferred ) break;
      }
      if( !p ) return;
      iSkip = sqlite3VdbeMakeLabel(v);
      sqlite3VdbeAddOp2(v, OP_FkIfZero, 1, iSkip);
    }

    pParse->disableTriggers = 1;
    sqlite3DeleteFrom(pParse, sqlite3SrcListDup(db, pName, 0), 0);
    pParse->disableTriggers = 0;

    /* If the DELETE has generated immediate foreign key constraint 
    ** violations, halt the VDBE and return an error at this point, before
    ** any modifications to the schema are made. This is because statement
    ** transactions are not able to rollback schema changes.  */






    sqlite3VdbeAddOp2(v, OP_FkIfZero, 0, sqlite3VdbeCurrentAddr(v)+2);
    sqlite3HaltConstraint(pParse, SQLITE_CONSTRAINT_FOREIGNKEY,
        OE_Abort, "foreign key constraint failed", P4_STATIC
    );


    if( iSkip ){
      sqlite3VdbeResolveLabel(v, iSkip);
    }
  }
}








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      /* Search for a deferred foreign key constraint for which this table
      ** is the child table. If one cannot be found, return without 
      ** generating any VDBE code. If one can be found, then jump over
      ** the entire DELETE if there are no outstanding deferred constraints
      ** when this statement is run.  */
      FKey *p;
      for(p=pTab->pFKey; p; p=p->pNextFrom){
        if( p->isDeferred || (db->flags & SQLITE_DeferFKs) ) break;
      }
      if( !p ) return;
      iSkip = sqlite3VdbeMakeLabel(v);
      sqlite3VdbeAddOp2(v, OP_FkIfZero, 1, iSkip);
    }

    pParse->disableTriggers = 1;
    sqlite3DeleteFrom(pParse, sqlite3SrcListDup(db, pName, 0), 0);
    pParse->disableTriggers = 0;

    /* If the DELETE has generated immediate foreign key constraint 
    ** violations, halt the VDBE and return an error at this point, before
    ** any modifications to the schema are made. This is because statement
    ** transactions are not able to rollback schema changes.  
    **
    ** If the SQLITE_DeferFKs flag is set, then this is not required, as
    ** the statement transaction will not be rolled back even if FK
    ** constraints are violated.
    */
    if( (db->flags & SQLITE_DeferFKs)==0 ){
      sqlite3VdbeAddOp2(v, OP_FkIfZero, 0, sqlite3VdbeCurrentAddr(v)+2);
      sqlite3HaltConstraint(pParse, SQLITE_CONSTRAINT_FOREIGNKEY,
          OE_Abort, "foreign key constraint failed", P4_STATIC
      );
    }

    if( iSkip ){
      sqlite3VdbeResolveLabel(v, iSkip);
    }
  }
}

Changes to test/fkey6.test.

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} {0 0 0}
do_test fkey6-1.22 {
  execsql {
    COMMIT;
  }
} {}




















































finish_test








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} {0 0 0}
do_test fkey6-1.22 {
  execsql {
    COMMIT;
  }
} {}

do_execsql_test fkey6-2.1 {
  CREATE TABLE p1(a PRIMARY KEY);
  INSERT INTO p1 VALUES('one'), ('two');
  CREATE TABLE c1(x REFERENCES p1);
  INSERT INTO c1 VALUES('two'), ('one');
}

do_execsql_test fkey6-2.2 {
  BEGIN;
    PRAGMA defer_foreign_keys = 1;
    DELETE FROM p1;
  ROLLBACK;
  PRAGMA defer_foreign_keys;
} {0}

do_execsql_test fkey6-2.3 {
  BEGIN;
    PRAGMA defer_foreign_keys = 1;
    DROP TABLE p1;
    PRAGMA vdbe_trace = 0;
  ROLLBACK;
  PRAGMA defer_foreign_keys;
} {0}

do_execsql_test fkey6-2.4 {
  BEGIN;
    PRAGMA defer_foreign_keys = 1;
    DELETE FROM p1;
    DROP TABLE c1;
  COMMIT;
  PRAGMA defer_foreign_keys;
} {0}

do_execsql_test fkey6-2.5 {
  DROP TABLE p1;
  CREATE TABLE p1(a PRIMARY KEY);
  INSERT INTO p1 VALUES('one'), ('two');
  CREATE TABLE c1(x REFERENCES p1);
  INSERT INTO c1 VALUES('two'), ('one');
}

do_execsql_test fkey6-2.6 {
  BEGIN;
    PRAGMA defer_foreign_keys = 1;
    INSERT INTO c1 VALUES('three');
    DROP TABLE c1;
  COMMIT;
  PRAGMA defer_foreign_keys;
} {0}


finish_test