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PostgreSQL documentation
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<para>
The <function>substring</> function with three parameters,
- <function>substring(<parameter>string</parameter> from
+ <function>substring(<replaceable>string</replaceable> from
<replaceable>pattern</replaceable> for
<replaceable>escape-character</replaceable>)</function>, provides
extraction of a substring that matches an SQL
<para>
The <function>substring</> function with two parameters,
- <function>substring(<parameter>string</parameter> from
+ <function>substring(<replaceable>string</replaceable> from
<replaceable>pattern</replaceable>)</function>, provides extraction of a substring
that matches a POSIX regular expression pattern. It returns null if
there is no match, otherwise the portion of the text that matched the