hi. "SQL specification" should be "SQL standard"?
+ another null vale and unequal to all other values. typo. should be "another null value" other places using subsection, many places in doc/src/sgml/nullvalues.sgml using "sub-section". + Notice two important behaviors: first, even though we passed in a null value to + to the <literal>set_config</literal> function, the <literal>current_setting</literal> there is two "to to". gmail has grammar checks, chatgpt can also help find typos. you can give it a try. + <programlisting> + BEGIN; + ALTER TABLE null_examples ADD CONSTRAINT value_not_1 CHECK (value != 1); + ROLLBACK; + </programlisting> + <screen> + BEGIN + ERROR: check constraint "value_not_1" of relation "null_examples" is violated by some row + ROLLBACK + </screen> + <programlisting> + BEGIN; + ALTER TABLE null_examples ADD CONSTRAINT value_not_10 CHECK (value != 10); + ROLLBACK; + </programlisting> + <screen> + BEGIN + ALTER TABLE + ROLLBACK + </screen> i think this part, BEGIN... ROLLBACK is not necessary. since if we add these check constraints, it won't influence the later(next) section.
