Example 1 shows an example of a trigger procedure in PL/pgSQL. Example 1. A PL/pgSQL Trigger Procedure This example trigger ensures that any time a row is inserted or updated in the table, the current user name and time are stamped into the row. And it checks that an employee’s nam...
for example these are equivalent: WHENdivision_by_zeroTHEN...WHENSQLSTATE’22012’THEN... When an error is caught by an EXCEPTION clause: the local variables of the PL/pgSQL function remain as they were when the error occurred, but all changes to persistent database state within the block ...
确保索引是最新的:定期重建索引可以确保查询性能。 使用EXPLAIN分析查询:EXPLAIN SELECT * FROM search_articles('example query'); 用来分析查询的执行计划,找出性能瓶颈。 限制结果数量:如果查询返回大量结果,考虑在SQL查询中使用 LIMIT 和OFFSET。 4. 实战应用 将上述配置和函数应用于实际的Web应用中,可以极大地提升...
一:理论 oracle 截取字符(substr),检索字符位置(instr) case when then else end语句使用 收藏 常用函数:substr和instr 1.SUBSTR(string,start_position,[length]) 求子字符串,返回字符串 解释:string 元字符串 start_position 开始位置(从0开始) length 可选项,子字符串的个数 For example: substr("ABCDEFG", ...
CREATETABLEhash_example(hash_key_columnDATE,DATAVARCHAR2(20))PARTITIONBYHASH(hash_key_cloumn)(PARTITIONpart01,PARTITIONpart02); 1. 2. 3. 4. 5. 6. 7. (4)、组合分区表 CREATETABLErange_hash_example(range_column_keyDATE,hash_column_keyINT,DATAVARCHAR2(20))PARTITIONBYRANGE(range_column_key)...
An example: GET DIAGNOSTICS integer_var = ROW_COUNT; The second method to determine the effects of a command is to check the special variable named FOUND, which is of type boolean. FOUND starts out false within each PL/pgSQLfunction call. It is set by each of the following types of sta...
postgres=# \d+ example_tbl Table "public.example_tbl"Column | Type | Collation | Nullable | Default | Storage | Compression | Stats target | Description---+---+---+---+---+---+---+---+---id | integer | | not null | | plain | ...
public | example_tbl | table | postgres | permanent | heap | 8192 bytes | public | pg_stat_statements | view | postgres | permanent | | 0 bytes | public | pg_stat_statements_info | view | postgres | permanent | | 0 bytes | ...
PostgreSQL 遵守 ANSI SQL 标准,该标准规定了语句终止是分号。在psql中可以通过添加分号并按 Enter 来表示 SQL 语句的结束。 如果不添加分号,psql将只提供一个新行供您继续输入,如下所示。 pagila_dev=# select*from film pagila_dev-#; 在添加分号之前不会执行查询。
In this example we have created a stored procedure with the user “postgres” and called it by using a “test” user who does not have access to the table. procedure_demo=#CREATEORREPLACEPROCEDUREgenre_traverse()LANGUAGEplpgsql SECURITY DEFINER ...