使用SELECT INTO语句将查询结果赋值给变量,然后在后续的SQL语句中直接引用该变量。 SELECT column_name INTO variable_name FROM table_name; 复制代码 使用SET语句为变量赋值,然后在后续的SQL语句中直接引用该变量。 SET variable_name = value; 复制代码 在PL/pgSQL中,可以使用DECLARE语句声明变量,并在BEGIN和END之...
SELECT COUNT(*) INTO v_int FROM pg_database WHERE datname like var_b; RETURN v_int; END; $$ LANGUAGE plpgsql; 然后我们从外部来调用这个函数并赋予变量 方法1 失败 [postgres@pg_qixun ~]$ psql -X -v a=postgres% -c 'select count_db(:a)' ERROR: syntax error at or near ":" LINE ...
select ename,job,sal into emp_table(0) from emp where empno=7369; dbms_output.put_line('index 0 : '||emp_table(0).ename); end; /第二类:非PL/SQL变量(来源于环境或宿主语言如C,java) SQLPLUS里可以使用绑定变量来接收PL/SQL块的返回值 VARIABLE return_code NUMBERvariable g_message VARCHAR2(...
1,直接给变量赋值:X:=200; Y=Y+(X*20); 2,通过SQL SELECT INTO 或FETCH INTO 给变量赋值: SELECT SUM(salart) , SUM(salary* 0.1) INTO total_salary, tatal_commission_value CONSTANT number := 0; FROM EMP WHERE DEPT = 10; 2,常量:与变量相似,但是其值在内部不能变定义时方式和变量相似,只是...
\prompt [TEXT] NAME prompt user to set internal variable \set [NAME [VALUE]] set internal variable, or list all if no parameters \unset NAME unset (delete) internal variable Large Objects \lo_export LOBOID FILE \lo_import FILE [COMMENT] ...
variable_name data_type [ NOT NULL ] [ { DEFAULT | := | = } expression ]; 其中,variable_name 是变量的名称,通常需要指定一个有意义的名称;data_type 是变量的类型,可以是任何 SQL 数据类型;如果指定了 NOT NULL,必须使用后面的表达式为变量指定初始值。 以下是一些变量声明的示例: user_id integer;...
] ) CREATE TYPE name ( INPUT = input_function, OUTPUT = output_function [, RECEIVE = receive_function ] [, SEND = send_function ] [, ANALYZE = analyze_function ] [, INTERNALLENGTH = { internal_length | VARIABLE } ] [, PASSEDBYVALUE ] [, ALIGNMENT = alignment ] [, STORAGE = stor...
方式一:into子句 代码语言:javascript 代码运行次数:0 运行 AI代码解释 SELECTselect_expressionsINTO[STRICT]targetFROM...;INSERT...RETURNINGexpressionsINTO[STRICT]target;UPDATE...RETURNINGexpressionsINTO[STRICT]target;DELETE...RETURNINGexpressionsINTO[STRICT]target; ...
custom_variable_classes = 'auto_explain' auto_explain.log_min_duration = 4s 51.数据库备份 select pg_start_backup('backup baseline'); select pg_stop_backup(); recovery.conf restore_command='cp /opt/buxlog/%f %p' 52.重建索引 REINDEX { INDEX | TABLE | DATABASE | SYSTEM } name [ FORCE...
Is Null –check if a value is null or not. Section 3. Joining Multiple Tables Joins –show you a brief overview of joins in PostgreSQL. Table aliases –describes how to use table aliases in the query. Inner Join–select rows from one table that have the corresponding rows in other tables...