CREATE FUNCTION defines a new function. CREATE OR REPLACE FUNCTION will either create a new function, or replace an existing definition. To be able to define a function, the user must have the USAGE privilege on the language. If a schema name is...
因此,要想安全地包围事先不知道地文本,你必须使用 quote_literal。 动态命令和 EXECUTE 的一个更大的例子在 Example 35-5 里, 这个例子制作病执行了一个定义新的函数的 CREATE FUNCTION 命令。 获取结果状态 有好几种方法可以判断一条命令的效果。第一个方法是使用 GET DIAGNOSTICS,它的形式如下: GET DIAGNOSTICS...
postgres=# create extension pginvoke;CREATE EXTENSION 4.再次查看已安装模块 已经创建成功。 5.查看函数创建脚本 postgres=# \sffunctionname is required postgres=# \sf pgEuropean CREATE OR REPLACE FUNCTION public.pgeuropean(real,real)RETURNS real LANGUAGE c PARALLEL RESTRICTED STRICT AS'$libdir/pginvoke...
/* function computing a datum's hash */typedefuint32 (*CCHashFN) (Datum datum);/* function computing equality of two datums */typedefbool(*CCFastEqualFN) (Datum a, Datum b);typedefstructcatcache {//cache IDintid;/* cache identifier --- see syscache.h *///cache的hash槽intcc_nbucke...
createorreplacefunctionauditlogfunc()returnstriggeras$example_table$begininsertintoaudit(emp_id,entry_date)values(new.id,current_timestamp);returnnew;end$example_table$languageplpgsql; (3)创建触发器函数 create trigger example_trigger after insertoncompanyforeach row executeprocedureauditlogfunc(); ...
CREATE OR REPLACE FUNCTION 函数名(参数名 参数类型, ,,,) RETURNS 返回值类型 AS $BODY$ DECLARE --变量声明 。。。 BEGIN --函数体 END; --函数结束 $BODY$ LANGUAGE ‘plpgsql’ VOLATILE; ALTER FUNCTION 函数名(变量) OWNER TO postgres; 2. ...
CREATE FUNCTION instr(varchar, integer) RETURNS integer AS $$ DECLARE v_string ALIAS FOR $1; index ALIAS FOR $2; BEGIN -- some computations using v_string and index here END; $$ LANGUAGE plpgsql; CREATE FUNCTION concat_selected_fields(in_t sometablename) RETURNS text AS $$ BEGIN RETURN...
Here's a small example to illustrate the problem: createtabletest_tableasselectnull::intasa,null::intasb;createfunctionrec_func(test_table)returnstextas$$select'Function got called'::text; $$languagesqlstrict;selectt, tisnullasis_null,coalesce(t,(1,2)::test_table), rec_func(t)fromtest_...
so you can use EXECUTE, example: CREATE OR REPLACE FUNCTION check_if_exist(id INTEGER, table_name varchar, table_column varchar) RETURNS BOOLEAN AS $$ DECLARE sql varchar; cnt int; BEGIN sql := 'SELECT count(*) FROM ' || quote_ident(table_name) || ' WHERE ' || quote_ident(table...
Example 1: How Does the RANK() Function Work in Postgres? In this example, we will utilize a “programming_languages” table that we have already created in our database: SELECT * FROM programming_languages; In the following example, the RANK() function is used on the “programming_language...