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本文实例讲述了postgreSQL存储过程用法。分享给大家供大家参考,具体如下: 转了N多的SQL语句,可是自己用时,却到处是坑啊,啊,啊!!!!!!!!!!!!!!! 想写一个获取表中最新ID值. 上代码 CREATE TABLE department( ID INT PRIMARY KEY NOT NULL, d_code VARCHAR(50), d_name VARCHAR(50) NOT NULL, d_parentID INT NOT NULL DEFAULT 0 ); --insert into department values(1,'001','office'); --insert into department values(2,'002','office',1); 下面要写个存储过程,以获取表中ID的最大值: drop function f_getNewID(text,text); create or replace function f_getNewID(myTableName text,myFeildName text) returns integer as $$ declare mysql text; myID integer; begin mysql:='select max( $1 ) from $2'; execute mysql into myID using myFeildName,myTableName; if myID is null or myID=0 then return 1; else return myID+1; end if; end; $$ language plpgsql; --大家可以试一下,上面这个是会报错的 --select f_getNewID('department','ID'); --出错! 看了官方文档,人家就是这么用的: EXECUTE 'SELECT count(*) FROM mytable WHERE inserted_by = $1 AND inserted <= $2' INTO c USING checked_user, checked_date; 你确定你看清楚了????? 确定你读完读懂了说明书????? --这个看了? --------------------------------------- EXECUTE 'SELECT count(*) FROM ' || quote_ident(tabname) || ' WHERE inserted_by = $1 AND inserted <= $2' INTO c USING checked_user, checked_date; --这个看了? --------------------------------------- EXECUTE 'UPDATE tbl SET ' || quote_ident(colname) || ' = ' || quote_literal(newvalue) || ' WHERE key = ' || quote_literal(keyvalue); --============================= --好吧, 我改 ------------------------------------------------------ drop function f_getNewID(text,text); create or replace function f_getNewID(myTableName text,myFeildName text) returns integer as $$ declare mysql text; myID integer; begin mysql:='select max(' || quote_ident(myFeildName) ||') from ' || quote_ident(myTableName); execute mysql into myID; --using myTableName,myFeildName; if myID is null or myID=0 then return 1; else return myID+1; end if; end; $$ language plpgsql; --============================== --漂亮,成功了! --But Why? --注意 对象(表名、字段名等)是不可以直接用变量的,要用 quote_ident() ------------------------------------------------------- postgres=# select f_getnewid('department','ID'); --错误: 字段 "ID" 不存在 --第1行select max("ID") from department ^ --查询: select max("ID") from department --背景: 在EXECUTE的第10行的PL/pgSQL函数f_getnewid(text,text) --=============================== --什么情况,ID怎么会有双引号,引号,号,号??? ---------------------------------------------------------- --这里要感谢大神:权宗亮@飞象数据 --改成这样: postgres=# select f_getnewid('department','id'); f_getnewid ------------ 2 (1 行记录) ----终于成功了!大小写还有区别吗??? --but why? --当在命令行输入 CREATE TABLE role( ID INT PRIMARY KEY NOT NULL, r_name VARCHAR(50) NOT NULL, r_paretnID INT NOT NULL DEFAULT 0 ); --结果在pgAdmin里看到的却是小写的 --同样,如果是在QUERY TOOLS 下用这样的语句创建还是 所有的字体名为小写 --如果我就想大写怎么办???? --要这样写 CREATE TABLE "RoleUPER"( "ID" INT PRIMARY KEY NOT NULL, r_name VARCHAR(50) NOT NULL, "r_paretnID" INT NOT NULL DEFAULT 0 ); --再用大象看看 可以了! 总结一下: 1、存储过程(FUNCITON)变量可以直接用 create or replace function f_getNewID(myTableName text,myFeildName text) returns integer as $$ declare mysql text; myID integer; begin mysql:='select max('|| $2 || ' ) from '||$1; execute mysql into myID using myFeildName,myTableName; if myID is null or myID=0 then return 1; else return myID+1; end if; end; $$ language plpgsql; 2、存储过程的对象不可以直接用变量,要用 3、$1 $2是 FUNCTION 参数的顺序,如1中的 $1 $2交换,USING 后面的不换 结果 : select max(myTableName) from myFeildname 4、注意:SQL语句中的大写全部会变成小写,要想大写存大,必须要用双引号。 附:一个完整postgreSQL 存储过程示例 CREATE OR REPLACE FUNCTION mt_f_avl_oee_period(i_station character varying,i_type int) RETURNS integer AS $BODY$ DECLARE v_start_hour character varying; v_end_hour character varying; v_start_time character varying; v_end_time character varying; v_start_datetime timestamp; v_end_datetime timestamp; v_type int := 0; v_rtn int; /* v_test9_count int; v_test9_success int; v_runningtime double precision; v_availablerate double precision; */ BEGIN -- hour = even, minute > 30 -- exists -- if i_type = 1 then SELECT EXTRACT(HOUR FROM CURRENT_TIME - interval '2 hours' ) into v_start_hour; --two hours ago SELECT EXTRACT(HOUR FROM CURRENT_TIME ) into v_end_hour; --get 'hour' of current time select v_start_hour || ':30' into v_start_time; select v_end_hour || ':30' into v_end_time; select mt_f_avl_oee_period_e(i_station, to_char( CURRENT_Date, 'YYYY-MM-DD'), v_start_time, v_end_time) into v_rtn; else SELECT EXTRACT(HOUR FROM CURRENT_TIME - interval '3 hours' ) into v_start_hour; SELECT EXTRACT(HOUR FROM CURRENT_TIME ) into v_end_hour; select v_start_hour || ':30' into v_start_time; select v_end_hour || ':00' into v_end_time; select mt_f_avl_oee_period_midnight(i_station, to_char( CURRENT_Date, 'YYYY-MM-DD'), v_start_time, v_end_time) into v_rtn; end if; RETURN 1; EXCEPTION WHEN others THEN RAISE; RETURN 0; END; $BODY$ LANGUAGE plpgsql VOLATILE COST 100; ALTER FUNCTION mt_f_avl_oee_period(i_station character varying,i_type int) OWNER TO postgres; 希望本文所述对大家PostgreSQL程序设计有所帮助。 |
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