SELECT datname FROM pg_database; 切换数据库 \c 数据库名 1、通过命令行查询 \d 数据库 —— 得到所有表的名字 \d 表名 —— 得到表结构 2、通过SQL语句查询 "select * from pg_tables" —— 得到当前db中所有表的信息(这里pg_tables是系统视图) "select tablename from pg_tables where schemaname=...
() # 定义参数化查询语句 query = "SELECT * FROM your_table WHERE column1 = %s AND column2 = %s" # 定义查询参数 params = ("value1", "value2") # 执行参数化查询 cur.execute(query, params) # 获取查询结果 result = cur.fetchall() # 处理查询结果 for row in result: print(row) # ...
query ="SELECT * FROM employees;"records = execute_query(connection, query)forrowinrecords:print("ID = ", row[0], )print("NAME = ", row[1])print("AGE = ", row[2]," ") 在这个例子中,execute_query函数接收一个数据库连接对象和一个SQL查询字符串作为参数,然后它创建了一个游标对象来执行...
在PostgreSQL 9.3中,将select值赋给变量可以使用"INTO"关键字和"EXECUTE"语句来实现。 首先,我们需要定义一个变量来存储select查询的结果。在函数中,可以使用DECLARE语句来声明一个变量,例如: DECLARE variable_name data_type; 其中,variable_name是变量的名称,data_type是变量的数据类型。 接下来,我们可以...
{ EXECUTE | ALL [ PRIVILEGES ] } ON FUNCTION func_name ([type, ...]) [, ...] TO { username | GROUP group_name | PUBLIC } [, ...] [ WITH GRANT OPTION ] GRANT { USAGE | ALL [ PRIVILEGES ] } ON LANGUAGE lang_name [, ...] TO { username | GROUP group_name | PUBLIC }...
PORTAL_MULTI_QUERY:用于处理以上三种情况之外的查询,包括嵌套查询等。 注:虽然说事务具有原子性,但是每一条SQL才是最小的具有原子性的单元。 策略选择 PG在生成计划树之后,执行计划树之前需要先选择执行策略。实际上PG会先通过调用CreatePortal()函数创建一个PortalData数据结构,然后调用PortalStart()里的ChoosePortalSt...
execute query, then execute each value in its result \gset [PREFIX] execute query and store result in psql variables \gx [(OPTIONS)] [FILE] as \g, but forces expanded output mode \q quit psql \watch [SEC] execute query every SEC secondsHelp \? [commands] show hel...
values for any needed parameters; and an execute step that runs a portal's query. In the case of a query that returns rows (SELECT, SHOW, etc), the execute step can be told to fetch only a limited number of rows, so that multiple execute steps might be needed to complete the ...
SELECTschemaname,tablename FROMpg_tables WHEREtableowner='postgres' ORDERBYtablename; QUERYPLAN −−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−...
statement,你想查看其执行计划的任何SELECT、INSERT、UPDATE、DELETE、VALUES、EXECUTE、DECLARE、CREATE TABLE AS或者CREATE MATERIALIZED VIEW AS语句。 常用组合 一般查询 --在不需要真正执行sql时,需把analyze去掉 explain analyze select … ; 查询缓存及详细信息 ...