declare r record; begin OLD.id := OLD.id+1; NEW.id := NEW.id+1; select 1 as id into r; raise notice '%, old.id:%. new.id:%', TG_NAME, OLD.id, NEW.id; return r; end; language plpgsql; CREATE FUNCTION postgres=#
*/ } else { /* Compute stored generated columns */ /* ... */ /* * If the target is a plain table, check the constraints of * the tuple. */ /* ... */ /* * Also check the tuple against the partition constraint, if * there is one; except that if we got here via tuple...
Perhaps you are convinced and you want to “upgrade” all your messy serial columns to this new identity column thing. (Note that you don’t have to “upgrade”. You can keep using serial columns the same way as before.) Here is a PL/pgSQL function that you can use: 也许你已经被说...
The following illustrates the syntax of the EXCEPT operator. SELECT select_list FROM A EXCEPT SELECT select_list FROM B; The queries that involve the EXCEPT need to follow these rules: The number of columns and their orders must be the same in the two queries. The data types of the respec...
SELECT * FROM crosstab( 'SELECT date, product, quantity FROM sales ORDER BY 1', 'SELECT DISTINCT product FROM sales ORDER BY 1' ) AS sales_pivot(date date, product1 int, product2 int, product3 int); 在上面的示例中,我们使用了两个查询作为crosstab函数的参数。第一个查询用于获取原始数据,第...
SELECTcolumn_name, data_type, is_nullable, column_default FROMinformation_schema.columns WHEREtable_name ='<table name>'; ci_database_test01=#SELECTcolumn_name, data_type, is_nullable, column_default ci_database_test01-#FROMinformation_schema.columns ...
1 \d+ tablename 回到顶部 7. 退出操作 1 q 回到顶部 8. 新建表 例1(主键) create table TESTCASE( id INTEGER, task_class INTEGER, age TEXT, PRIMARY KEY(id, task_class) ); 例2(自增SERIAL) create table CREATETASK_CHKID_N( id SERIAL PRIMARY KEY, ...
frequency of null elements (expressed in the same terms:* the fraction of non-null rows that contain at least one null element). If* this member is omitted, the column is presumed to contain no null elements.** Note: in current usage for tsvector columns, the stavalues elements are of*...
PostgreSQL 的查询功能是丰富的。前面章节讨论了 WITH 子句,现在来看 SELECT 语句中使用的另外两个可选特性。 集合查询 PostgreSQL 提供 UNION、INTERSECT 和 EXCEPT 子句用于 SELECT 语句之间的交互。UNION 将第二个 SELECT 语句的结果附加到第一个。 INTERSECT 返回两个 SELECT 语句均有的行。EXCEPT 返回第一个 SEL...
postgres=# explain (selectidfromtest_dm)except(selectidfromtest_dm2); QUERY PLAN---HashSetOpExcept(cost=0.00..383303.38rows=1000000width=4)->Append (cost=0.00..355803.34rows=11000017width=4)->Subquery Scanon"*SELECT* 1" (cost=0.00..32346.00rows=1000000width=4)->Seq Scanontest_dm (cost=...