diff options
Diffstat (limited to 'doc/src')
| -rw-r--r-- | doc/src/sgml/ref/create_table.sgml | 30 | ||||
| -rw-r--r-- | doc/src/sgml/ref/insert.sgml | 31 | ||||
| -rw-r--r-- | doc/src/sgml/ref/update.sgml | 7 |
3 files changed, 48 insertions, 20 deletions
diff --git a/doc/src/sgml/ref/create_table.sgml b/doc/src/sgml/ref/create_table.sgml index 9f8b59de50a..155866c7c83 100644 --- a/doc/src/sgml/ref/create_table.sgml +++ b/doc/src/sgml/ref/create_table.sgml @@ -842,15 +842,27 @@ WITH ( MODULUS <replaceable class="parameter">numeric_literal</replaceable>, REM <para> The clauses <literal>ALWAYS</literal> and <literal>BY DEFAULT</literal> - determine how the sequence value is given precedence over a - user-specified value in an <command>INSERT</command> statement. - If <literal>ALWAYS</literal> is specified, a user-specified value is - only accepted if the <command>INSERT</command> statement - specifies <literal>OVERRIDING SYSTEM VALUE</literal>. If <literal>BY - DEFAULT</literal> is specified, then the user-specified value takes - precedence. See <xref linkend="sql-insert"/> for details. (In - the <command>COPY</command> command, user-specified values are always - used regardless of this setting.) + determine how explicitly user-specified values are handled in + <command>INSERT</command> and <command>UPDATE</command> commands. + </para> + + <para> + In an <command>INSERT</command> command, if <literal>ALWAYS</literal> is + selected, a user-specified value is only accepted if the + <command>INSERT</command> statement specifies <literal>OVERRIDING SYSTEM + VALUE</literal>. If <literal>BY DEFAULT</literal> is selected, then the + user-specified value takes precedence. See <xref linkend="sql-insert"/> + for details. (In the <command>COPY</command> command, user-specified + values are always used regardless of this setting.) + </para> + + <para> + In an <command>UPDATE</command> command, if <literal>ALWAYS</literal> is + selected, any update of the column to any value other than + <literal>DEFAULT</literal> will be rejected. If <literal>BY + DEFAULT</literal> is selected, the column can be updated normally. + (There is no <literal>OVERRIDING</literal> clause for the + <command>UPDATE</command> command.) </para> <para> diff --git a/doc/src/sgml/ref/insert.sgml b/doc/src/sgml/ref/insert.sgml index e829c61642d..a6cec6b02ea 100644 --- a/doc/src/sgml/ref/insert.sgml +++ b/doc/src/sgml/ref/insert.sgml @@ -206,10 +206,19 @@ INSERT INTO <replaceable class="parameter">table_name</replaceable> [ AS <replac <term><literal>OVERRIDING SYSTEM VALUE</literal></term> <listitem> <para> - Without this clause, it is an error to specify an explicit value - (other than <literal>DEFAULT</literal>) for an identity column defined - as <literal>GENERATED ALWAYS</literal>. This clause overrides that - restriction. + If this clause is specified, then any values supplied for identity + columns will override the default sequence-generated values. + </para> + + <para> + For an identity column defined as <literal>GENERATED ALWAYS</literal>, + it is an error to insert an explicit value (other than + <literal>DEFAULT</literal>) without specifying either + <literal>OVERRIDING SYSTEM VALUE</literal> or <literal>OVERRIDING USER + VALUE</literal>. (For an identity column defined as + <literal>GENERATED BY DEFAULT</literal>, <literal>OVERRIDING SYSTEM + VALUE</literal> is the normal behavior and specifying it does nothing, + but <productname>PostgreSQL</productname> allows it as an extension.) </para> </listitem> </varlistentry> @@ -219,8 +228,8 @@ INSERT INTO <replaceable class="parameter">table_name</replaceable> [ AS <replac <listitem> <para> If this clause is specified, then any values supplied for identity - columns defined as <literal>GENERATED BY DEFAULT</literal> are ignored - and the default sequence-generated values are applied. + columns are ignored and the default sequence-generated values are + applied. </para> <para> @@ -238,7 +247,8 @@ INSERT INTO <replaceable class="parameter">table_name</replaceable> [ AS <replac <term><literal>DEFAULT VALUES</literal></term> <listitem> <para> - All columns will be filled with their default values. + All columns will be filled with their default values, as if + <literal>DEFAULT</literal> were explicitly specified for each column. (An <literal>OVERRIDING</literal> clause is not permitted in this form.) </para> @@ -258,8 +268,11 @@ INSERT INTO <replaceable class="parameter">table_name</replaceable> [ AS <replac <term><literal>DEFAULT</literal></term> <listitem> <para> - The corresponding column will be filled with - its default value. + The corresponding column will be filled with its default value. An + identity column will be filled with a new value generated by the + associated sequence. For a generated column, specifying this is + permitted but merely specifies the normal behavior of computing the + column from its generation expression. </para> </listitem> </varlistentry> diff --git a/doc/src/sgml/ref/update.sgml b/doc/src/sgml/ref/update.sgml index f58dcd8877b..4840bf560c1 100644 --- a/doc/src/sgml/ref/update.sgml +++ b/doc/src/sgml/ref/update.sgml @@ -142,8 +142,11 @@ UPDATE [ ONLY ] <replaceable class="parameter">table_name</replaceable> [ * ] [ <term><literal>DEFAULT</literal></term> <listitem> <para> - Set the column to its default value (which will be NULL if no - specific default expression has been assigned to it). + Set the column to its default value (which will be NULL if no specific + default expression has been assigned to it). An identity column will be + set to a new value generated by the associated sequence. For a + generated column, specifying this is permitted but merely specifies the + normal behavior of computing the column from its generation expression. </para> </listitem> </varlistentry> |