SELECT [ ALL | DISTINCT [ ON ( expression [, ...] ) ] ] * | expression [ AS output_name ] [, ...] [ FROM from_item [, ...] ] [ WHERE condition ] [ GROUP BY expression [, ...] ] [ HAVING condition [, ...] ] [ { UNION | INTERSECT | EXCEPT } [ ALL ] select ]...
3.案例解析案例1：SQL来源于长沙生产环境，SQL如下（平均运行时间在1000ms左右）SELECTt1.questionid,t1.questioncode,t1.typelevel,t1.creator,t1.createtime,t1.updatetime,t1.status,t1.title,t1.subjectid,t1.grade,t1.term,t1.item,t1.degree,t1.sharerange,t1.defaultscore,t1.paragraphid,t1.orgid,t1.s...
58 * variable-length fields start here, but we allow direct access to 59 * proargtypes 60 */61oidvector proargtypes;/* parameter types (excludes OUT params) */6263#ifdefCATALOG_VARLEN64Oid proallargtypes[1];/* all param types (NULL if IN only) */65char proargmodes[1];/* paramete...
UPDATE, or DELETE operation, either once per modified row, or once per SQL statement.UPDATE triggers can moreover be set to fire only if certain columns are mentioned in the SET clause of the UPDATE statement.Triggers can also fire for TRUNCATE statements.If a trigger event occurs, the tri...
定位一个游标。 MOVE [ direction { FROM | IN } ] cursor_nameNOTIFY生成一个通知。NOTIFY namePREPARE创建一个准备好的查询。PREPARE plan_name [ (data_type [, ...] ) ] AS statementREINDEX重建索引。REINDEX { DATABASE | TABLE | INDEX } name [ FORCE ]...
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;...
Example 1: Declaring and Using a Variable Code: -- Use an anonymous DO block to declare a variable DO $$ DECLARE employee_count INTEGER; -- Declare an integer variable BEGIN -- Assign a value to the variable using a SELECT statement ...
statement --逻辑块(pl/pgsql代码块) [ RETURN return_value;] END; $body$ LANGUAGE plpgsql 1.1.2 关键字说明 CREATE [ OR REPLACE ] FUNCTION 创建函数关键字 IN 表示该参数为输入参数 OUT 表示该参数为输出参数 DECLARE 定义变量列表 BEGIN 正文代码开始 ...
CURSOR cursor_name is select_statement 。 2.打开游标: OPEN打开游标。游标只能打开一次。 格式: OPEN cursor_name 。 3.提取游标数据: 检索游标结果集中的数据,放入指定的变量之中。 格式: FETCH cursor_name INTO variable_name 。 4.关闭游标:
stmt :='delete from emp where deptno = :dept_array';/* A Dynamic SQL String with a bind variable */c :=DBMS_SQL.OPEN_CURSOR;/* Open a Cursor! */DBMS_SQL.PARSE(c, stmt, DBMS_SQL.NATIVE);/* Parse the Dynamic SQL , making it happen on the native database to which is connected...