pgsql: doc: Rearrange the logical operator truth tables.

doc: Rearrange the logical operator truth tables.

The table for AND and OR is somewhat difficult to read, and it
lists only six of the nine combinations of operands and leaves the
rest to commutativity. Therefore, it is ill-prepared for a new
non-commutative operator. This commit adjusts the page to present
AND, OR, and NOT in separate tables with the operand values as
headers and the results in the cells.

Author: Vik Fearing <vik(at)postgresfriends(dot)org>
Discussion: https://postgr.es/m/37c76707-e6fa-4ee3-b57f-aa0bf1b0bba8%40postgresfriends.org

Branch
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master

Details
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https://git.postgresql.org/pg/commitdiff/c074737f687f604b64f6ee830fccbbe854719823

Modified Files
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doc/src/sgml/func/func-logical.sgml | 70 +++++++++++++++++++++----------------
1 file changed, 40 insertions(+), 30 deletions(-)