使用 GET DIAGNOSTICS 进行错误检查

下列示例展示如何使用 GET DIAGNOSTICS 语句来显示错误信息。该示例展示名为 disp_sqlstate_err( ) 的 GBase 8s ESQL/C 错误显示例程：

void disp_sqlstate_err()
{
int j;
EXEC SQL BEGIN DECLARE SECTION;
    int exception_count;
    char overflow[2];
    int exception_num=1;
    char class_id[255];
    char subclass_id[255];
    char message[255];
    int messlen;
    char sqlstate_code[6];
    int i;
EXEC SQL END DECLARE SECTION;
    printf("---------------------------------");
    printf("-------------------------\n");
    printf("SQLSTATE: 
    printf("SQLCODE: %d\n", SQLCODE);
    printf("\n");
    EXEC SQL get diagnostics :exception_count = NUMBER,
        :overflow = MORE;
    printf("EXCEPTIONS:  Number=%d\t", exception_count);
    printf("More? %s\n", overflow);
    for (i = 1; i <= exception_count; i++)
    {
        EXEC SQL get diagnostics  exception :i
            :sqlstate_code = RETURNED_SQLSTATE,
            :class_id = CLASS_ORIGIN, :subclass_id = SUBCLASS_ORIGIN,
            :message = MESSAGE_TEXT, :messlen = MESSAGE_LENGTH;
        printf("- - - - - - - - - - - - - - - - - - - -\n");
        printf("EXCEPTION %d: SQLSTATE=%s\n", i, sqlstate_code);
        message[messlen-1] ='\0';
        printf("MESSAGE TEXT: %s\n", message);
        j = stleng(class_id);
        while((class_id[j] == '\0') ||
              (class_id[j] == ' '))
            j--;
        class_id[j+1] = '\0';
        printf("CLASS ORIGIN: 
        j = stleng(subclass_id);
        while((subclass_id[j] == '\0') ||
              (subclass_id[j] == ' '))
            j--;
        subclass_id[j+1] = '\0';
        printf("SUBCLASS ORIGIN: 
    }
    printf("---------------------------------");
    printf("-------------------------\n");
}