动态SQL有哪些类型的语句格式

这篇文章主要讲解了“动态SQL有哪些类型的语句格式”，文中的讲解内容简单清晰，易于学习与理解，下面请大家跟着小编的思路慢慢深入，一起来研究和学习“动态SQL有哪些类型的语句格式”吧！

1.Dynamic SQL Format 1

EXECUTE IMMEDIATE SQLStatement     {USING TransactionObject} ;

eg:
string            Mysql
Mysql = "CREATE TABLE Employee "&
    +"(emp_id integer not null,"&
    +"dept_id integer not null, "&
    +"emp_fname char(10) not null, "&
    +"emp_lname char(20) not null)"
EXECUTE IMMEDIATE :Mysql ;

2.Dynamic SQL Format 2

PREPARE DynamicStagingArea FROM SQLStatement     {USING TransactionObject} ;
EXECUTE DynamicStagingArea USING {ParameterList} ;

eg:
INT        Emp_id_var = 56
PREPARE SQLSA
    FROM "DELETE FROM employee WHERE emp_id=?" ;
EXECUTE SQLSA USING :Emp_id_var ;

3.Dynamic SQL Format 3

DECLARE Cursor | Procedure     DYNAMIC CURSOR | PROCEDURE      FOR DynamicStagingArea ;
PREPARE DynamicStagingArea FROM SQLStatement     {USING TransactionObject} ;
OPEN DYNAMIC Cursor     {USING ParameterList} ;
EXECUTE DYNAMIC Procedure    {USING ParameterList} ;
FETCH Cursor | Procedure     INTO HostVariableList ;
CLOSE Cursor | Procedure ;
eg:
integer Emp_id_var

DECLARE my_cursor DYNAMIC CURSOR FOR SQLSA ;
PREPARE SQLSA FROM "SELECT emp_id FROM employee" ;
OPEN DYNAMIC my_cursor ;
FETCH my_cursor INTO :Emp_id_var ;
CLOSE my_cursor ;

4.Dynamic SQL Format 4

DECLARE Cursor | Procedure     DYNAMIC CURSOR | PROCEDURE      FOR DynamicStagingArea ;
PREPARE DynamicStagingArea FROM SQLStatement    {USING TransactionObject} ;
DESCRIBE DynamicStagingArea    INTO DynamicDescriptionArea ;
OPEN DYNAMIC Cursor | Procedure    USING DESCRIPTOR DynamicDescriptionArea ;
EXECUTE DYNAMIC Cursor | Procedure    USING DESCRIPTOR DynamicDescriptionArea ;
FETCH Cursor | Procedure     USING DESCRIPTOR DynamicDescriptionArea ;
CLOSE Cursor | Procedure ;

eg:

string Stringvar, Sqlstatement
integer Intvar
Sqlstatement = "SELECT emp_id FROM employee"
PREPARE SQLSA FROM :Sqlstatement ;
DESCRIBE SQLSA INTO SQLDA ;
DECLARE my_cursor DYNAMIC CURSOR FOR SQLSA ;
OPEN DYNAMIC my_cursor USING DESCRIPTOR SQLDA ;
FETCH my_cursor USING DESCRIPTOR SQLDA ;

// If the FETCH is successful, the output
// descriptor array will contain returned
// values from the first row of the result set.
// SQLDA.NumOutputs contains the number of
// output descriptors.
// The SQLDA.OutParmType array will contain
// NumOutput entries and each entry will contain
// an value of the enumerated data type ParmType
// (such as TypeInteger!, or TypeString!).

CHOOSE CASE SQLDA.OutParmType[1]
CASE TypeString!
        Stringvar = GetDynamicString(SQLDA, 1)
    CASE TypeInteger!
        Intvar = GetDynamicNumber(SQLDA, 1)

END CHOOSE
CLOSE my_cursor ;

感谢各位的阅读，以上就是“动态SQL有哪些类型的语句格式”的内容了，经过本文的学习后，相信大家对动态SQL有哪些类型的语句格式这一问题有了更深刻的体会，具体使用情况还需要大家实践验证。这里是亿速云，小编将为大家推送更多相关知识点的文章，欢迎关注！