Declare RECORD variables and types A specific RECORD TYPE corresponding to a fixed number (and datatype) of underlying table columns can simplify the job of defining variables. %TYPE is used to declare a field
DECLARE语句用于在存储过程或函数中声明变量,并为其分配数据类型。我们还提供了一个示例代码来演示DECLARE语句的使用方法。希望通过本文,读者可以更好地理解和运用DECLARE语句来存储和处理数据。 参考资料: [MySQL DECLARE statement]( [MySQL Data Types](
-- Create a variable with a default > DECLARE VARIABLE myvar INT DEFAULT 5; > VALUES (myvar); 5 -- Setting a variable > SET VAR myvar = (SELECT sum(c1) FROM VALUES(1), (2) AS T(c1); > VALUES (myvar); 3 -- Variables are the outermost scope. > SELECT myvar, t.myvar, sessi...
声明变量的语法如下: Variable_name [CONSTANT] databyte [NOT NULL][:=|DEFAULT expression] 注意:可以在声明变量的同时给变量强制性的加上NOT NULL约束条件,此时变量在初始化时必须赋值。 给变量赋值 给变量赋值有两种方式: . 直接给变量赋值 X:=200; Y=Y+(X*20); . 通过SQL SELECT INTO 或FETCH INTO给...
For more information about system data types, seeData Types (Transact-SQL). For more information about CLR user-defined types or alias data types, seeCREATE TYPE (Transact-SQL). =value Assigns a value to the variable in-line. The value can be a constant or an expression, but it must ei...
DECLARE@myVariableASVARCHAR='abc';DECLARE@myNextVariableASCHAR='abc';--The following query returns 1SELECTDATALENGTH(@myVariable),DATALENGTH(@myNextVariable); GO B. 在 CAST 和 CONVERT 中使用 varchar 时,显示n的默认值 以下示例显示在和函数中使用char或CAST数据类型时,CONVERT的默认值为 30。
For more information about system data types, seeData Types (Transact-SQL). For more information about CLR user-defined types or alias data types, seeCREATE TYPE (Transact-SQL). =value Assigns a value to the variable in-line. The value can be a constant or an expression, but it must ei...
DECLARE -- Global variables num1 number := 95; num2 number := 85; BEGIN dbms_output.put_line('Outer Variable num1: ' || num1); dbms_output.put_line('Outer Variable num2: ' || num2); DECLARE -- Local variables num1 number := 195; num2 number := 185; BEGIN dbms_output.put...
1. DECLARE 说明以下你要声明的部分 2. Type 声明是类型 table_t 类型的名字 3. IS TABLE OF 指定是一个集合的表的数组类型, 简单的来说就是一个可以存储一列多行的数据类型 , my_emp 指出在哪个表上( 存在的表 ) %ROWTYPE 指在表上的行的数据类型. ...
For more information about CLR user-defined types or alias data types, see CREATE TYPE (Transact-SQL).= value Assigns a value to the variable in-line. The value can be a constant or an expression, but it must either match the variable declaration type or be implicitly convertible to that...