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DBLINK_BUILD_SQL_UPDATE(3)                      PostgreSQL 9.5.0 Documentation

NAME
       dblink_build_sql_update - builds an UPDATE statement using a local
       tuple, replacing the primary key field values with alternative supplied
       values

SYNOPSIS
       dblink_build_sql_update(text relname,
                               int2vector primary_key_attnums,
                               integer num_primary_key_atts,
                               text[] src_pk_att_vals_array,
                               text[] tgt_pk_att_vals_array) returns text

DESCRIPTION
       dblink_build_sql_update can be useful in doing selective replication of
       a local table to a remote database. It selects a row from the local
       table based on primary key, and then builds a SQL UPDATE command that
       will duplicate that row, but with the primary key values replaced by
       the values in the last argument. (To make an exact copy of the row,
       just specify the same values for the last two arguments.) The UPDATE
       command always assigns all fields of the row -- the main difference
       between this and dblink_build_sql_insert is that it's assumed that the
       target row already exists in the remote table.

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.

       src_pk_att_vals_array
           Values of the primary key fields to be used to look up the local
           tuple. Each field is represented in text form. An error is thrown
           if there is no local row with these primary key values.

       tgt_pk_att_vals_array
           Values of the primary key fields to be placed in the resulting
           UPDATE command. Each field is represented in text form.

RETURN VALUE
       Returns the requested SQL statement as text.

NOTES
       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_update('foo', '1 2', 2, '{"1", "a"}', '{"1", "b"}');
                              dblink_build_sql_update
           -------------------------------------------------------------
            UPDATE foo SET f1='1',f2='b',f3='1' WHERE f1='1' AND f2='b'
           (1 row)

PostgreSQL 9.5.0                     2016           DBLINK_BUILD_SQL_UPDATE(3)