esqlc方面的资料.txt

db2 指定某个字符串中的第几个字符的更新

   return (0);
}
2.5.2 ADHOC程序
该程序的功能是：用户输入任意SQL语句，并执行和打印结果。 


#include <stdio.h>
#include <stdlib.h>
#include <string.h>
/* Defines for BINDING */
/*初试化SQLDA*/
int init_da (SQLDA **DAPointer, int DAsqln);
/*为存放列数据的sd_column结构申请空间*/
int alloc_host_vars (SQLDA *sqldaPointer);
/*释放SQLDA所申请的空间*/
void free_da (SQLDA *sqldaPointer);
/*获取列名信息*/
char * readColName (SQLDA *sqldaPointer, short sd_columnIndex, char * buffer);
/*获取列数据*/
char * readCol (SQLDA *sqldaPointer, short sd_columnIndex, char * buffer);
#ifdef __cplusplus
}
#endif
/*定义最大列数*/
#define MAX_COLUMNS255 

#define MAX_CHAR_FOR_DOUBLE20
#define MAX_CHAR_FOR_LONG15
#define MAX_CHAR_FOR_DATETIME30
#define MAX_CHAR_FOR_DEFAULT100
EXEC SQL INCLUDE SQLCA ;
EXEC SQL INCLUDE SQLDA ; 

#define SQLSTATE sqlca.sqlstate
#define SQLCODE sqlca.sqlcode
/*处理SQL语句*/
int process_statement( char * ) ;
int main() {
  int rc ;
  char st[1024];
  char tmpstr[1024];
/*获得SQL语句*/
printf("Please enter the any sql statement:");
  gets( st);
  /* 处理该语句 */
  rc = process_statement( st ) ;
/*打印处理结果*/
  printf( "%d", rc);
  printf("the sqlcode is %d",SQLCODE);
}
/******************************************************************************
* FUNCTION : process_statement
* 处理SQL语句
*****************************************************************************/
int process_statement ( char * sqlInput ) { 

  int counter = 0 ;
  SQLDA * sqldaPointer ;
  short sqlda_d ; /* Total columns */
  short idx;
  char buffer[4096];
  char varname[1024];
  char colnamelist[4096];
  EXEC SQL BEGIN DECLARE SECTION ;
     char st[1024] ;
  EXEC SQL END DECLARE SECTION ;
  strcpy( st, sqlInput ) ;
  /* 为SQLDA结构申请空间" */
  if (init_da( &sqldaPointer, MAX_COLUMNS ) == -1)
{
        return -1;
}
/*准备SQL语句*/
  EXEC SQL PREPARE statement1 from :st ;
  if (SQLCODE < 0)
{
        free_da(sqldaPointer);
    return SQLCODE;
    }
/*获取查询列的信息到SQLDA结构*/
  EXEC SQL DESCRIBE statement1 USING DESCRIPTOR sqldaPointer ;
/* 如果SQLCODE为0，则表示为SELECT语句 */
  if ( SQLCODE != 0 ) {
free_da(sqldaPointer);
return SQLCODE;
  } /* end if */
  sqlda_d = sqldaPointer->sd_sqld ;
  if ( sqlda_d > 0 ) {
     /* 为存放列数据的sd_column结构申请空间 */
     if (alloc_host_vars( sqldaPointer ) == -1)
{free_da(sqldaPointer);
return -1;
}
     /*声明游标*/
     EXEC SQL DECLARE pcurs CURSOR FOR statement1 ;
    /打开游标*/
     EXEC SQL OPEN pcurs ;
     if (SQLCODE < 0)
     return SQLCODE;
     /*取一行数据到SQLDA结构*/
     EXEC SQL FETCH pcurs INTO DESCRIPTOR sqldaPointer;
     if (SQLCODE < 0)
{
 EXEC SQL CLOSE pcurs ;
 return SQLCODE;
       }
     /*显示列标题 */
     colnamelist[0] = 0;
     for ( idx=0; idx< sqlda_d; idx++)
{ strcat(colnamelist, readColName(sqldaPointer, idx, buffer));
 if (idx < sqlda_d -1)
strcat(colnamelist, ",");
}
     /* 显示行数据*/
     while ( SQLCODE == 0 ) {
      counter++ ;
        for ( idx=0; idx< sqlda_d; idx++)      
         printf("%s",readCol(sqldaPointer, idx, buffer));
    EXEC SQL FETCH pcurs INTO DESCRIPTOR sqldaPointer ;
     }  /* endwhile */
    /*关闭游标*/
     EXEC SQL CLOSE pcurs ;
 EXEC SQL DEALLOCATE CURSOR pcurs;
     /* 释放为SQLDA申请的空间 */
     free_da( sqldaPointer ) ;
  } else { /* 不是SELECT语句*/
     EXEC SQL EXECUTE statement1 ;
     free_da( sqldaPointer ) ;
     if (SQLCODE < 0)
return SQLCODE;
  }  /* end if */
  return( 0 ) ;
}     /* end of program : ADHOC.CP */ 

/******************************************************************************* PROCEDURE : init_da
*为SQLDA分配空间。使用SQLDASIZE 获得SQLDA的大小。如果返回-1，则表示分配
*空间不成功。
******************************************************************************/
int init_da (SQLDA **DAPointer, int DAsqln) {
int idx;
  *DAPointer = (SQLDA *)malloc(SYB_SQLDA_SIZE(DAsqln));
  if (*DAPointer == NULL) 
     return (-1);
  memset (*DAPointer, '\0', SYB_SQLDA_SIZE(DAsqln));
  (*DAPointer)->sd_sqln = DAsqln;
  (*DAPointer)->sd_sqld = 0;
  return 0;
}
/******************************************************************************* FUNCTION : alloc_host_vars
*为存放列数据的sd_column结构申请空间。如果返回-1，则表示不能获得足够内存。
******************************************************************************/
int alloc_host_vars (SQLDA *sqldaPointer) {
  short idx;
  
  for (idx = 0; idx < sqldaPointer->sd_sqld; idx++) {
     switch (sqldaPointer->sd_column[idx].sd_datafmt.datatype ) {
case CS_CHAR_TYPE:
case CS_VARCHAR_TYPE:
sqldaPointer->sd_column[idx].sd_datafmt.datatype = CS_CHAR_TYPE;
 sqldaPointer->sd_column[idx].sd_sqldata = (char *) malloc (sqldaPointer->sd_column[idx].sd_sqllen + 1 );
sqldaPointer->sd_column[idx].sd_sqllen ++;
sqldaPointer->sd_column[idx].sd_datafmt.format = CS_FMT_NULLTERM;
break; 

case CS_TINYINT_TYPE:
case CS_SMALLINT_TYPE:
case CS_INT_TYPE:
case CS_VOID_TYPE:
case CS_USHORT_TYPE:
sqldaPointer->sd_column[idx].sd_datafmt.datatype = CS_CHAR_TYPE;
 sqldaPointer->sd_column[idx].sd_sqldata = (char *) malloc (MAX_CHAR_FOR_LONG);
sqldaPointer->sd_column[idx].sd_sqllen = MAX_CHAR_FOR_LONG;
sqldaPointer->sd_column[idx].sd_datafmt.format = CS_FMT_NULLTERM;
break; 

case CS_REAL_TYPE:
case CS_FLOAT_TYPE:
case CS_BIT_TYPE:
case CS_MONEY_TYPE:
case CS_MONEY4_TYPE:
sqldaPointer->sd_column[idx].sd_datafmt.datatype = CS_CHAR_TYPE;
sqldaPointer->sd_column[idx].sd_sqldata = (char *) malloc (MAX_CHAR_FOR_DOUBLE);
sqldaPointer->sd_column[idx].sd_sqllen = MAX_CHAR_FOR_DOUBLE;
sqldaPointer->sd_column[idx].sd_datafmt.format = CS_FMT_NULLTERM;
break; 

case CS_DATETIME_TYPE:
case CS_DATETIME4_TYPE:
sqldaPointer->sd_column[idx].sd_datafmt.datatype = CS_CHAR_TYPE;
sqldaPointer->sd_column[idx].sd_sqldata = (char *) malloc (MAX_CHAR_FOR_DATETIME);
sqldaPointer->sd_column[idx].sd_sqllen = MAX_CHAR_FOR_DATETIME;
sqldaPointer->sd_column[idx].sd_datafmt.format = CS_FMT_NULLTERM;
break; 

case CS_NUMERIC_TYPE:
case CS_DECIMAL_TYPE:
sqldaPointer->sd_column[idx].sd_datafmt.datatype = CS_CHAR_TYPE;
sqldaPointer->sd_column[idx].sd_sqldata = (char *) malloc (sqldaPointer->sd_column[idx].sd_datafmt.precision + 3 );
sqldaPointer->sd_column[idx].sd_sqllen = sqldaPointer->sd_column[idx].sd_datafmt.precision + 3;
sqldaPointer->sd_column[idx].sd_datafmt.format = CS_FMT_NULLTERM;
break; 

default:
sqldaPointer->sd_column[idx].sd_datafmt.datatype = CS_CHAR_TYPE;
 sqldaPointer->sd_column[idx].sd_sqldata = (char *) malloc (MAX_CHAR_FOR_DEFAULT);
sqldaPointer->sd_column[idx].sd_sqllen = MAX_CHAR_FOR_DEFAULT;
sqldaPointer->sd_column[idx].sd_datafmt.format = CS_FMT_NULLTERM;
break;
     } /* endswitch */
     if (sqldaPointer->sd_column[idx].sd_sqldata == NULL) {
return (-1);
     }
  } /* endfor */
 return 0;
}
/*******************************************************************************  FUNCTION : free_da
*  释放SQLDA申请的空间。
******************************************************************************/
void free_da (SQLDA *sqldaPointer) {
  short idx;
  for (idx = 0; idx < sqldaPointer->sd_sqld; idx++) {
     free (sqldaPointer->sd_column[idx].sd_sqldata);
  } /* endfor */
  free (sqldaPointer);
}
/******************************************************************************* PROCEDURE : readColName
* 返回列名
******************************************************************************/
char * readColName (SQLDA *sqldaPointer, short sd_columnIndex, char * buffer) {
  strcpy(buffer, sqldaPointer->sd_column[sd_columnIndex].sd_datafmt.name);
  return buffer;
}
/******************************************************************************* PROCEDURE : readCol
* 返回列数据。
**************************************************