Postgresql 中文操作指南

dblink_build_sql_delete

dblink_build_sql_delete —使用为主键字段值提供的的值构建 DELETE 语句

dblink_build_sql_delete — builds a DELETE statement using supplied values for primary key field values

Synopsis

dblink_build_sql_delete(text relname,
                        int2vector primary_key_attnums,
                        integer num_primary_key_atts,
                        text[] tgt_pk_att_vals_array) returns text

Description

dblink_build_sql_delete 在将本地表选择性复制到远程数据库时可能很有用。它构建了一个 SQL DELETE 命令，该命令将删除具有给定主键值的行的。

dblink_build_sql_delete can be useful in doing selective replication of a local table to a remote database. It builds an SQL DELETE command that will delete the row with the given primary key values.

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.

  • primary_key_attnums

    • Attribute numbers (1-based) of the primary key fields, for example 1 2.

  • num_primary_key_atts

    • The number of primary key fields.

  • tgt_pk_att_vals_array

    • Values of the primary key fields to be used in the resulting DELETE command. Each field is represented in text form.

Return Value

返回所请求的 SQL 语句作为文本。

Returns the requested SQL statement as text.

Notes

截至 PostgreSQL 9.0， primary_key_attnums 中的属性编号被解释为逻辑列编号，对应于该列在 SELECT * FROM relname 中的位置。以前版本将数字解释为物理列位置。如果在表的生命周期内删除了指示列左侧的任何列，则会有差异。

As of PostgreSQL 9.0, the attribute numbers in primary_key_attnums are interpreted as logical column numbers, corresponding to the column’s position in SELECT * FROM relname. Previous versions interpreted the numbers as physical column positions. There is a difference if any column(s) to the left of the indicated column have been dropped during the lifetime of the table.

Examples

SELECT dblink_build_sql_delete('"MyFoo"', '1 2', 2, '{"1", "b"}');
           dblink_build_sql_delete
---------------------------------------------
 DELETE FROM "MyFoo" WHERE f1='1' AND f2='b'
(1 row)