PostgreSQL?? ??? ??? ??? ??
??
PostgreSQL? ??? ????? ??? ? ?? ??? ??? ???? ??? ??? ??? ?????.
??? zip() ??(??? ??) ??)
??? ?? ? ??? ????? ARRAY[] ???? ?? unnest() ??? ??? ? ????.
SELECT ARRAY[a,b] AS ab FROM ( SELECT unnest('{a,b,c}'::text[]) AS a, unnest('{d,e,f}'::text[]) AS b ) x;
??:
ab ------- {a,d} {b,e} {c,f}
zip() ??? ??? ??? ??
? ??? ???? ?? ??? ??? PostgreSQL? ??? ?? ?? ?? array_agg_mult()? ?????:
CREATE AGGREGATE array_agg_mult (anyarray) ( SFUNC = array_cat, STYPE = anyarray, INITCOND = '{}' );
??:
SELECT array_agg_mult(ARRAY[ARRAY[a,b]]) AS ab FROM ( SELECT unnest('{a,b,c}'::text[]) AS a, unnest('{d,e,f}'::text[]) AS b ) x;
??:
{{a,d},{b,e},{c,f}}
??, zip2() ??? ??? ??? ? ????. array_agg_mult():
CREATE OR REPLACE FUNCTION zip2(anyarray, anyarray) RETURNS SETOF anyarray LANGUAGE SQL AS $func$ SELECT array_agg_mult(ARRAY[ARRAY[a,b]]) FROM (SELECT unnest() AS a, unnest() AS b) x; $func$
??:
SELECT zip2('{a,b,c}'::text[], '{d,e,f}'::text[]);
??:
{{a,d},{b,e},{c,f}}
Postgres 9.5(array_agg(?? ???))
Postgres 9.5 ????? array_agg(array ???) ??? ??? ??? ??? ?? ??? ? ?? ??? ?? ?? ??? ?? ? ???? ???? ?????. ???? array_agg_mult() ??? ?????.
? ??? PostgreSQL?? ??? ??? ??? ????? ????? ??? ?? ????? ?? ?????. ??? ??? PHP ??? ????? ?? ?? ??? ?????!

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MySQL ????? ?? ??? ?? ?????? ????? ???? ???? ?????. ??, ???? ??? ???? ??? ????? ?????. ?? ?? ?? ?? ??? ?????. ?? ??, ?? ? ??? ?? ???? ??? ????? ??? ???? ??????. ??, ???? ????? ??????? ? ??? ???? ?? ??? ?? ? ? ????? ?? ?? ? ???? ?? ????? ?? ??? ??? ??? ?????. ??, ??? ?? ??? ?? ??? ???? ????, ??? ??, ?? ???? ?? ? ??? ??? ?????. MySQL? readuncommitted ? readcommi? ?????.

MySQL? ?? ???? ?? ??? ??? ? A??, ?? MVCC ? GAP ?? ??? ?? ??? ?? ? ?? ???? ??? ???? ???? ?? ?? ??? ????. ?? ?? ??? ??? ?? (??)? ????? ??? ??? ????? ?? ?? ??? ????? 1. ??? ??? (read committed)? ?? ? ???? ?? ? ??? ?? ? ??? ?? ? ?? ?? ?? ?? ? ? ????. ???, ??? ??? ????? ??? ??;

MySQL? ? ????? ??? ??? ????? ?? ?? ??? ?? ???????. 1. Windows ??? : MySQL ?? ?????? ? ??? ????? (?? ??? ????? C : \ programfiles \ mysql \ mysqlserverx.x \ bin), "? ???"→ "??"→ "Advanced System ??"→ "?? ??", "??? ??", MySQlb in wors in mysqlb in wors in mysqlb in world in that the the the the the seel worl ?? ????? ?? ???? MySQL? ??????-Version Versification; 2.Macos ? Linux ??? : Bash ??? ?? ~/.bashrc ?? ~/.bash_

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AconnectionpoolisacacheofdatabaseConnection? ??? ??????

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