查询SELECT语句用于从数据库中查询数据,当在PL/SQL中使用SELECT语句时,要与INTO子句一起使用,查询的 返回值被赋予INTO子句中的变量,变量的声明是在DELCARE中.SELECT INTO语法如下: SELECT [DISTICT|ALL]{*|column[,column,...]} INTO (variable[,variable,...] |record) FROM {table|(sub-query)}[alias] ...
c:\>psql exampledb < user.sql // 将user.sql文件导入到exampled数据库中 postgres=# \h select // 精细显示SQL命令中的select命令的使用方法 postgres=# \l // 显示所有数据库 postgres=# \dt // 显示当前数据库中的所有表 postgres=# \d [table_name] // 显示当前数据库的指定表的表结构 postgres...
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...
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 variable = item [ , ... ] ; 这条命令允许我们检索系统状态...
UNDEF[INE] variable ... 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13. 14. 1.3 应用详解 &:如果变量已定义时,则引用变量并替换;如果变量无定义,交互输入替换值,替换,但不定义变量,即如果后面又出现该替换变量,则仍需要交互输入替换值,当然也可以使用define提前定义替换变量值,规避交互输入。
No parallel infrastructure can completely eliminate this problem, because any global variable is a risk. There's no general mechanism for ensuring that every global variable in the worker will have the same value that it does in the initiating backend; even if we could ensure that, some functio...
CREATE EVENT TRIGGER name ON event [WHEN filter_variable IN (filter_value[,...]) [AND ...]] EXECUTE PROCUDURE function_name() 定义触发器函数 CREATE OR REPLACE FUNCTION event_trigger_drops_function() RETURN EVENT_TRIGGER LANGUAGE plpgsql AS $$ DECLARE Obj record; BEGIN INSERT INTO drop_au...
variable { := | = } expression; 执行无结果调用 PERFORM query; 通常被用来判断是否有记录,例如 PERFORM select 1 from tbl where xxx limit 1; if found then xxx else xxx end if; 执行返回单行的表达式或QUERY,并将结果存入变量。 SELECT select_expressions INTO [STRICT] target FROM ...; INSER...
stmt :='delete from emp where deptno = :dept_array';/* A Dynamic SQL String with a bind variable */c :=DBMS_SQL.OPEN_CURSOR;/* Open a Cursor! */DBMS_SQL.PARSE(c, stmt, DBMS_SQL.NATIVE);/* Parse the Dynamic SQL , making it happen on the native database to which is connected...
populates# the table with data, and then retrieves the data.run:nodeclient.js# Environment variable used by the `client.js` script to create# a new PostgreSQL client.env:# The hostname used to communicate with the PostgreSQL service containerPOSTGRES_HOST:postgres# The default PostgreSQL port...