mysql - group_concat 的替代方案

Question

在 mysql 中是否有 GROUP_CONCAT 的替代方案。由于 GROUP_CONCAN 的最大长度约束是 1024，我需要一个替代方案。我不能更改 GROUP_CONCAN_MAX_LENGTH 的值，我的要求不允许它。所以我需要连接字符串按 ID 分组。

Answer 1

可以引用这篇文章:SQL trick: overcoming GROUP_CONCAT limitation in special cases

SELECT
  SUBSTRING(
    CONCAT(
      GROUP_CONCAT(
        IF(actor_id BETWEEN 1 AND 100, CONCAT(',', last_name), '')
        SEPARATOR ''
      ),
      GROUP_CONCAT(
        IF(actor_id BETWEEN 101 AND 200, CONCAT(',', last_name), '')
        SEPARATOR ''
      )
    ),
    2
  ) AS result
FROM actor
\G

*************************** 1. row ***************************
result: AKROYD,AKROYD,ASTAIRE,BAILEY,BARRYMORE,BERGEN,BERRY,BERRY,BERRY,BLOOM,BOLGER,BRIDGES,BRODY,CAGE,CAGE,CHAPLIN,CHASE,COSTNER,CRAWFORD,CRONYN,CRUISE,CRUZ,DAMON,DAVIS,DAY-LEWIS,DEAN,DEGENERES,DENCH,DEPP,DUKAKIS,FAWCETT,GABLE,GOLDBERG,GRANT,GUINESS,GUINESS,HACKMAN,HARRIS,HAWKE,HOFFMAN,HOFFMAN,HOPKINS,HUDSON,HUNT,JOHANSSON,JOHANSSON,JOLIE,JOVOVICH,KEITEL,KILMER,KILMER,KILMER,LOLLOBRIGIDA,MARX,MCCONAUGHEY,MCCONAUGHEY,MCKELLEN,MCQUEEN,MIRANDA,MOSTEL,MOSTEL,NEESON,NEESON,NICHOLSON,OLIVIER,OLIVIER,PALTROW,PALTROW,PECK,PECK,PECK,PENN,PESCI,PHOENIX,PINKETT,PITT,POSEY,PRESLEY,SINATRA,SOBIESKI,STALLONE,STREEP,SWANK,TANDY,TAUTOU,TEMPLE,TORN,TORN,TRACY,VOIGHT,WAHLBERG,WAHLBERG,WAYNE,WILLIAMS,WILLIS,WILLIS,WINSLET,WOOD,WRAY,ZELLWEGER,AKROYD,ALLEN,ALLEN,ALLEN,BACALL,BAILEY,BALE,BALL,BASINGER,BENING,BENING,BERGMAN,BIRCH,BOLGER,BRODY,BULLOCK,CARREY,CHASE,CLOSE,CRAWFORD,CRONYN,CROWE,DAVIS,DAVIS,DEAN,DEE,DEE,DEGENERES,DEGENERES,DENCH,DEPP,DERN,DREYFUSS,DUKAKIS,DUNST,FAWCETT,GARLAND,GARLAND,GARLAND,GIBSON,GOODING,GOODING,GUINESS,HACKMAN,HARRIS,HARRIS,HESTON,HOFFMAN,HOPE,HOPKINS,HOPKINS,HOPPER,HOPPER,HURT,JACKMAN,JACKMAN,JOHANSSON,KEITEL,KEITEL,KILMER,KILMER,LEIGH,MALDEN,MANSFIELD,MCDORMAND,MCKELLEN,MCQUEEN,MONROE,MONROE,NOLTE,NOLTE,NOLTE,NOLTE,PENN,PFEIFFER,REYNOLDS,RYDER,SILVERSTONE,SILVERSTONE,STREEP,SUVARI,TANDY,TEMPLE,TEMPLE,TEMPLE,TOMEI,TORN,TRACY,WALKEN,WEST,WEST,WILLIAMS,WILLIAMS,WILLIS,WILSON,WINSLET,WITHERSPOON,WOOD,ZELLWEGER,ZELLWEGER
1 row in set (0.00 sec)