Postgresql 中文操作指南

dblink_get_pkey

dblink_get_pkey — 返回关系主键字段的位置和字段名

dblink_get_pkey — returns the positions and field names of a relation’s primary key fields

Synopsis

dblink_get_pkey(text relname) returns setof dblink_pkey_results

Description

dblink_get_pkey 提供有关本地数据库中关系的主键的信息。这有时有助于生成要发送到远程数据库的查询。

dblink_get_pkey provides information about the primary key of a relation in the local database. This is sometimes useful in generating queries to be sent to remote databases.

Arguments

  • relname

    • Name of a local relation, for example foo or myschema.mytab. Include double quotes if the name is mixed-case or contains special characters, for example "FooBar"; without quotes, the string will be folded to lower case.

Return Value

为每个主键字段返回一行，如果关系没有主键，则没有行。结果行类型定义为：

Returns one row for each primary key field, or no rows if the relation has no primary key. The result row type is defined as

CREATE TYPE dblink_pkey_results AS (position int, colname text);

position 列从 1 运行至 N ;它是主键中的字段数，而不是表中的列数。

The position column simply runs from 1 to N; it is the number of the field within the primary key, not the number within the table’s columns.

Examples

CREATE TABLE foobar (
    f1 int,
    f2 int,
    f3 int,
    PRIMARY KEY (f1, f2, f3)
);
CREATE TABLE

SELECT * FROM dblink_get_pkey('foobar');
 position | colname
----------+---------
        1 | f1
        2 | f2
        3 | f3
(3 rows)