insert.c

sqlite数据库管理系统开放源码

/*
** 2001 September 15
**
** The author disclaims copyright to this source code.  In place of
** a legal notice, here is a blessing:
**
**    May you do good and not evil.
**    May you find forgiveness for yourself and forgive others.
**    May you share freely, never taking more than you give.
**
*************************************************************************
** This file contains C code routines that are called by the parser
** to handle INSERT statements in SQLite.
**
** $Id: insert.c,v 1.94 2004/02/24 01:05:33 drh Exp $
*/
#include "sqliteInt.h"

/*
** This routine is call to handle SQL of the following forms:
**
**    insert into TABLE (IDLIST) values(EXPRLIST)
**    insert into TABLE (IDLIST) select
**
** The IDLIST following the table name is always optional.  If omitted,
** then a list of all columns for the table is substituted.  The IDLIST
** appears in the pColumn parameter.  pColumn is NULL if IDLIST is omitted.
**
** The pList parameter holds EXPRLIST in the first form of the INSERT
** statement above, and pSelect is NULL.  For the second form, pList is
** NULL and pSelect is a pointer to the select statement used to generate
** data for the insert.
**
** The code generated follows one of three templates.  For a simple
** select with data coming from a VALUES clause, the code executes
** once straight down through.  The template looks like this:
**
**         open write cursor to <table> and its indices
**         puts VALUES clause expressions onto the stack
**         write the resulting record into <table>
**         cleanup
**
** If the statement is of the form
**
**   INSERT INTO <table> SELECT ...
**
** And the SELECT clause does not read from <table> at any time, then
** the generated code follows this template:
**
**         goto B
**      A: setup for the SELECT
**         loop over the tables in the SELECT
**           gosub C
**         end loop
**         cleanup after the SELECT
**         goto D
**      B: open write cursor to <table> and its indices
**         goto A
**      C: insert the select result into <table>
**         return
**      D: cleanup
**
** The third template is used if the insert statement takes its
** values from a SELECT but the data is being inserted into a table
** that is also read as part of the SELECT.  In the third form,
** we have to use a intermediate table to store the results of
** the select.  The template is like this:
**
**         goto B
**      A: setup for the SELECT
**         loop over the tables in the SELECT
**           gosub C
**         end loop
**         cleanup after the SELECT
**         goto D
**      C: insert the select result into the intermediate table
**         return
**      B: open a cursor to an intermediate table
**         goto A
**      D: open write cursor to <table> and its indices
**         loop over the intermediate table
**           transfer values form intermediate table into <table>
**         end the loop
**         cleanup
*/
void sqliteInsert(
  Parse *pParse,        /* Parser context */
  SrcList *pTabList,    /* Name of table into which we are inserting */
  ExprList *pList,      /* List of values to be inserted */
  Select *pSelect,      /* A SELECT statement to use as the data source */
  IdList *pColumn,      /* Column names corresponding to IDLIST. */
  int onError           /* How to handle constraint errors */
){
  Table *pTab;          /* The table to insert into */
  char *zTab;           /* Name of the table into which we are inserting */
  const char *zDb;      /* Name of the database holding this table */
  int i, j, idx;        /* Loop counters */
  Vdbe *v;              /* Generate code into this virtual machine */
  Index *pIdx;          /* For looping over indices of the table */
  int nColumn;          /* Number of columns in the data */
  int base;             /* VDBE Cursor number for pTab */
  int iCont, iBreak;    /* Beginning and end of the loop over srcTab */
  sqlite *db;           /* The main database structure */
  int keyColumn = -1;   /* Column that is the INTEGER PRIMARY KEY */
  int endOfLoop;        /* Label for the end of the insertion loop */
  int useTempTable;     /* Store SELECT results in intermediate table */
  int srcTab;           /* Data comes from this temporary cursor if >=0 */
  int iSelectLoop;      /* Address of code that implements the SELECT */
  int iCleanup;         /* Address of the cleanup code */
  int iInsertBlock;     /* Address of the subroutine used to insert data */
  int iCntMem;          /* Memory cell used for the row counter */
  int isView;           /* True if attempting to insert into a view */

  int row_triggers_exist = 0; /* True if there are FOR EACH ROW triggers */
  int before_triggers;        /* True if there are BEFORE triggers */
  int after_triggers;         /* True if there are AFTER triggers */
  int newIdx = -1;            /* Cursor for the NEW table */

  if( pParse->nErr || sqlite_malloc_failed ) goto insert_cleanup;
  db = pParse->db;

  /* Locate the table into which we will be inserting new information.
  */
  assert( pTabList->nSrc==1 );
  zTab = pTabList->a[0].zName;
  if( zTab==0 ) goto insert_cleanup;
  pTab = sqliteSrcListLookup(pParse, pTabList);
  if( pTab==0 ){
    goto insert_cleanup;
  }
  assert( pTab->iDb<db->nDb );
  zDb = db->aDb[pTab->iDb].zName;
  if( sqliteAuthCheck(pParse, SQLITE_INSERT, pTab->zName, 0, zDb) ){
    goto insert_cleanup;
  }

  /* Ensure that:
  *  (a) the table is not read-only, 
  *  (b) that if it is a view then ON INSERT triggers exist
  */
  before_triggers = sqliteTriggersExist(pParse, pTab->pTrigger, TK_INSERT, 
                                       TK_BEFORE, TK_ROW, 0);
  after_triggers = sqliteTriggersExist(pParse, pTab->pTrigger, TK_INSERT,
                                       TK_AFTER, TK_ROW, 0);
  row_triggers_exist = before_triggers || after_triggers;
  isView = pTab->pSelect!=0;
  if( sqliteIsReadOnly(pParse, pTab, before_triggers) ){
    goto insert_cleanup;
  }
  if( pTab==0 ) goto insert_cleanup;

  /* If pTab is really a view, make sure it has been initialized.
  */
  if( isView && sqliteViewGetColumnNames(pParse, pTab) ){
    goto insert_cleanup;
  }

  /* Allocate a VDBE
  */
  v = sqliteGetVdbe(pParse);
  if( v==0 ) goto insert_cleanup;
  sqliteBeginWriteOperation(pParse, pSelect || row_triggers_exist, pTab->iDb);

  /* if there are row triggers, allocate a temp table for new.* references. */
  if( row_triggers_exist ){
    newIdx = pParse->nTab++;
  }

  /* Figure out how many columns of data are supplied.  If the data
  ** is coming from a SELECT statement, then this step also generates
  ** all the code to implement the SELECT statement and invoke a subroutine
  ** to process each row of the result. (Template 2.) If the SELECT
  ** statement uses the the table that is being inserted into, then the
  ** subroutine is also coded here.  That subroutine stores the SELECT
  ** results in a temporary table. (Template 3.)
  */
  if( pSelect ){
    /* Data is coming from a SELECT.  Generate code to implement that SELECT
    */
    int rc, iInitCode;
    iInitCode = sqliteVdbeAddOp(v, OP_Goto, 0, 0);
    iSelectLoop = sqliteVdbeCurrentAddr(v);
    iInsertBlock = sqliteVdbeMakeLabel(v);
    rc = sqliteSelect(pParse, pSelect, SRT_Subroutine, iInsertBlock, 0,0,0);
    if( rc || pParse->nErr || sqlite_malloc_failed ) goto insert_cleanup;
    iCleanup = sqliteVdbeMakeLabel(v);
    sqliteVdbeAddOp(v, OP_Goto, 0, iCleanup);
    assert( pSelect->pEList );
    nColumn = pSelect->pEList->nExpr;

    /* Set useTempTable to TRUE if the result of the SELECT statement
    ** should be written into a temporary table.  Set to FALSE if each
    ** row of the SELECT can be written directly into the result table.
    **
    ** A temp table must be used if the table being updated is also one
    ** of the tables being read by the SELECT statement.  Also use a 
    ** temp table in the case of row triggers.
    */
    if( row_triggers_exist ){
      useTempTable = 1;
    }else{
      int addr = sqliteVdbeFindOp(v, OP_OpenRead, pTab->tnum);
      useTempTable = 0;
      if( addr>0 ){
        VdbeOp *pOp = sqliteVdbeGetOp(v, addr-2);
        if( pOp->opcode==OP_Integer && pOp->p1==pTab->iDb ){
          useTempTable = 1;
        }
      }
    }

    if( useTempTable ){
      /* Generate the subroutine that SELECT calls to process each row of
      ** the result.  Store the result in a temporary table
      */
      srcTab = pParse->nTab++;
      sqliteVdbeResolveLabel(v, iInsertBlock);
      sqliteVdbeAddOp(v, OP_MakeRecord, nColumn, 0);
      sqliteVdbeAddOp(v, OP_NewRecno, srcTab, 0);
      sqliteVdbeAddOp(v, OP_Pull, 1, 0);
      sqliteVdbeAddOp(v, OP_PutIntKey, srcTab, 0);
      sqliteVdbeAddOp(v, OP_Return, 0, 0);

      /* The following code runs first because the GOTO at the very top
      ** of the program jumps to it.  Create the temporary table, then jump
      ** back up and execute the SELECT code above.
      */
      sqliteVdbeChangeP2(v, iInitCode, sqliteVdbeCurrentAddr(v));
      sqliteVdbeAddOp(v, OP_OpenTemp, srcTab, 0);
      sqliteVdbeAddOp(v, OP_Goto, 0, iSelectLoop);
      sqliteVdbeResolveLabel(v, iCleanup);
    }else{
      sqliteVdbeChangeP2(v, iInitCode, sqliteVdbeCurrentAddr(v));
    }
  }else{
    /* This is the case if the data for the INSERT is coming from a VALUES
    ** clause
    */
    SrcList dummy;
    assert( pList!=0 );
    srcTab = -1;
    useTempTable = 0;
    assert( pList );
    nColumn = pList->nExpr;
    dummy.nSrc = 0;
    for(i=0; i<nColumn; i++){
      if( sqliteExprResolveIds(pParse, &dummy, 0, pList->a[i].pExpr) ){
        goto insert_cleanup;
      }
      if( sqliteExprCheck(pParse, pList->a[i].pExpr, 0, 0) ){
        goto insert_cleanup;
      }
    }
  }

  /* Make sure the number of columns in the source data matches the number
  ** of columns to be inserted into the table.
  */
  if( pColumn==0 && nColumn!=pTab->nCol ){
    sqliteErrorMsg(pParse, 
       "table %S has %d columns but %d values were supplied",
       pTabList, 0, pTab->nCol, nColumn);
    goto insert_cleanup;
  }
  if( pColumn!=0 && nColumn!=pColumn->nId ){
    sqliteErrorMsg(pParse, "%d values for %d columns", nColumn, pColumn->nId);
    goto insert_cleanup;
  }

  /* If the INSERT statement included an IDLIST term, then make sure
  ** all elements of the IDLIST really are columns of the table and 
  ** remember the column indices.
  **
  ** If the table has an INTEGER PRIMARY KEY column and that column
  ** is named in the IDLIST, then record in the keyColumn variable
  ** the index into IDLIST of the primary key column.  keyColumn is
  ** the index of the primary key as it appears in IDLIST, not as
  ** is appears in the original table.  (The index of the primary
  ** key in the original table is pTab->iPKey.)
  */
  if( pColumn ){
    for(i=0; i<pColumn->nId; i++){
      pColumn->a[i].idx = -1;
    }
    for(i=0; i<pColumn->nId; i++){
      for(j=0; j<pTab->nCol; j++){
        if( sqliteStrICmp(pColumn->a[i].zName, pTab->aCol[j].zName)==0 ){
          pColumn->a[i].idx = j;
          if( j==pTab->iPKey ){
            keyColumn = i;
          }
          break;
        }
      }
      if( j>=pTab->nCol ){
        if( sqliteIsRowid(pColumn->a[i].zName) ){
          keyColumn = i;
        }else{
          sqliteErrorMsg(pParse, "table %S has no column named %s",
              pTabList, 0, pColumn->a[i].zName);
          pParse->nErr++;
          goto insert_cleanup;
        }
      }
    }
  }