MySql如何手動取得自增主鍵

mysql手動取得自增主鍵的方法：透過建立預存程序外加函數的方式維護一張sequences表來取得數據，程式碼為【last_number = last_number increment_by】。

mysql手動取得自增主鍵的方法：

• 透過建立儲存程序外加函數的方式維護一張sequences表來取得資料（一次解決終身受用）。

• 可以指定每次自增的大小，以及初始數。

select nextval('TESTDATA') AS batchId
CREATE DEFINER=`admin`@`%` FUNCTION `nextval`(seq_name VARCHAR (50)) RETURNS bigint(20)
BEGIN
  UPDATE
    SEQUENCES
  SET
    last_number = last_number + increment_by
  WHERE sequence_name = seq_name;
  RETURN currval (seq_name);
END;

CREATE DEFINER=`admin`@`%` FUNCTION `currval`(seq_name VARCHAR (50)) RETURNS bigint(20)
    NO SQL
BEGIN
  
  SELECT
    last_number INTO @VALUE
  FROM
    SEQUENCES
  WHERE sequence_name = seq_name;
  RETURN @VALUE;
END;

DROP TABLE IF EXISTS `sequences`;
CREATE TABLE `sequences`  (
  `sequence_owner` varchar(30) CHARACTER SET utf8mb4 COLLATE utf8mb4_bin NOT NULL,
  `sequence_name` varchar(30) CHARACTER SET utf8mb4 COLLATE utf8mb4_bin NOT NULL,
  `min_value` bigint(20) NULL DEFAULT 1,
  `max_value` bigint(20) NULL DEFAULT NULL,
  `increment_by` bigint(20) NOT NULL DEFAULT 1,
  `cycle_flag` varchar(1) CHARACTER SET utf8mb4 COLLATE utf8mb4_bin NULL DEFAULT NULL,
  `order_flag` varchar(1) CHARACTER SET utf8mb4 COLLATE utf8mb4_bin NULL DEFAULT NULL,
  `cache_size` bigint(20) NOT NULL,
  `last_number` bigint(20) NOT NULL,
  PRIMARY KEY (`sequence_name`) USING BTREE,
  UNIQUE INDEX `sel`(`sequence_owner`, `sequence_name`) USING BTREE
) ENGINE = InnoDB CHARACTER SET = utf8mb4 COLLATE = utf8mb4_bin ROW_FORMAT = Compact;
 
-- ----------------------------
-- Records of sequences
-- ----------------------------
INSERT INTO `sequences` VALUES ('SCM', 'TESTDATA', 1, 9999999999, 1, 'N', 'Y', 20, 0);
INSERT INTO `sequences` VALUES ('SCM', 'SEQ', 1, 9999999999, 1, 'N', 'N', 20, 0);
 
SET FOREIGN_KEY_CHECKS = 1;

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