动态SQL四种类型的语句格式

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 ;

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