[sqlite] Sqlite3_exec_stmt

[Ing-Long Eric Kuo]

I love sqlite3_exec, but I also like prepared statements.  Here's a function
I wrote to make it easier to execute prepared statement.  I have only tested
with SELECT and INSERT.

Hope someone finds it useful.

-Eric


#include "sqliteInt.h"
#include "os.h"
#include <ctype.h>

/*
** Execute SQL code.  Return one of the SQLITE_ success/failure
** codes.  Also write an error message into memory obtained from
** malloc() and make *pzErrMsg point to that message.
**
** If the SQL is a query, then for each row in the query result
** the xCallback() function is called.  pArg becomes the first
** argument to xCallback().  If xCallback=NULL then no callback
** is invoked, even for queries.
*/
int sqlite3_exec_stmt(
  sqlite3_stmt *pStmt,           /* The SQL to be executed */
  sqlite3_callback xCallback, /* Invoke this callback routine */
  void *pArg,                 /* First argument to xCallback() */
  char **pzErrMsg             /* Write error messages here */
){
  int rc = SQLITE_OK;
  sqlite3 *db = 0;
  char **azCols = 0;

  int nRetry = 0;
  int nChange = 0;
  int nCallback;

  if( pStmt ==0 ) return SQLITE_OK;
  db = sqlite3_db_handle(pStmt);
  while( (rc==SQLITE_OK || (rc==SQLITE_SCHEMA && (++nRetry)<2))){
    int nCol;
    char **azVals = 0;

    db->nChange += nChange;
    nCallback = 0;

    nCol = sqlite3_column_count(pStmt);
    azCols = sqliteMalloc(2*nCol*sizeof(const char *) + 1);
    if( azCols==0 ){
      goto exec_out;
    }

    while( 1 ){
      int i;
      rc = sqlite3_step(pStmt);

      /* Invoke the callback function if required */
      if( xCallback && (SQLITE_ROW==rc || 
          (SQLITE_DONE==rc && !nCallback && db->flags&SQLITE_NullCallback))
){
        if( 0==nCallback ){
          for(i=0; i<nCol; i++){
            azCols[i] = (char *)sqlite3_column_name(pStmt, i);
          }
          nCallback++;
        }
        if( rc==SQLITE_ROW ){
          azVals = &azCols[nCol];
          for(i=0; i<nCol; i++){
            azVals[i] = (char *)sqlite3_column_text(pStmt, i);
          }
        }
        if( xCallback(pArg, nCol, azVals, azCols) ){
          rc = SQLITE_ABORT;
          goto exec_out;
        }
      }

      if( rc!=SQLITE_ROW ){              
        if( db->pVdbe==0 ){
          nChange = db->nChange;
        }       
        break;
      }
    }

    sqliteFree(azCols);
    azCols = 0;
  }

exec_out:
  if( azCols ) sqliteFree(azCols);

  rc = sqlite3ApiExit(0, rc);
  if( rc!=SQLITE_OK && rc==sqlite3_errcode(db) && pzErrMsg ){
    *pzErrMsg = sqlite3_malloc(1+strlen(sqlite3_errmsg(db)));
    if( *pzErrMsg ){
      strcpy(*pzErrMsg, sqlite3_errmsg(db));
    }
  }else if( pzErrMsg ){
    *pzErrMsg = 0;
  }

  sqlite3_reset(pStmt);

  assert( (rc&db->errMask)==rc );
  return rc;
}


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