<\/span><\/h2>\n\n\n\n\u5982\u679c\u6570\u636e\u6709\u552f\u4e00\u5217\uff0c\u4e0d\u91cd\u590d(\u6bd4\u5982\u81ea\u589e)\uff0c\u90a3\u4e48\u53ef\u4ee5\u76f4\u63a5\u5220\u9664\u3002\u6bd4\u5982\u6709id\u5217 a,b,c \u91cd\u590d<\/p>\n\n\n\n
Delete from table where id not in (select max (id) from table group a,b,c)<\/p>\n\n\n\n
\u540e\u9762\u90fd\u662f\u65e0\u552f\u4e00ID\u7684\u60c5\u51b5\u3002<\/strong><\/span><\/p>\n\n\n\n<\/span>\u6d4b\u8bd5\u6570\u636e<\/span><\/h2>\n\n\n\n\u5982\u4e0b\u6784\u9020\u51e0\u884c\u6570\u636e\u5305\u542b\u91cd\u590d\u7684\u3002\u5176\u4e2d\u6211\u4eec\u5047\u5b9aid\u662f\u53ef\u4ee5\u552f\u4e00\u533a\u5206\u7684\u5b57\u6bb5\uff0c\u53ea\u662f\u91cd\u590d\u4e86\u3002<\/p>\n\n\n\n
gbase> create table tc1 (id int, name varchar(100));\nQuery OK, 0 rows affected (Elapsed: 00:00:00.60)\n\ngbase> insert into tc1 values (1,'111');\nQuery OK, 1 row affected (Elapsed: 00:00:00.40)\n\ngbase> insert into tc1 values (1,'111');\nQuery OK, 1 row affected (Elapsed: 00:00:00.25)\n\ngbase> insert into tc1 values (2,'222');\nQuery OK, 1 row affected (Elapsed: 00:00:00.40)\n\ngbase> insert into tc1 values (3,'333');\nQuery OK, 1 row affected (Elapsed: 00:00:00.22)\n\ngbase>\ngbase> select * from tc1;\n+------+------+\n| id | name |\n+------+------+\n| 1 | 111 |\n| 1 | 111 |\n| 2 | 222 |\n| 3 | 333 |\n+------+------+\n4 rows in set (Elapsed: 00:00:00.00)\n<\/code><\/pre>\n\n\n\n<\/span>\u6570\u636e\u8f6c\u50a8\u6cd5<\/span><\/h2>\n\n\n\n\u6b64\u65b9\u6cd5\u64cd\u4f5c\u903b\u8f91\u6700\u7b80\u5355\u3002\u672c\u65b9\u6848\u5904\u7406\u903b\u8f91\u5982\u4e0b\uff1a<\/p>\n\n\n\n
1\u3001\u65b0\u5efa\u4e00\u4e2a\u8868
2\u3001\u4f7f\u7528 insert into \u65b0\u8868 as select distinct * from\u8001\u8868\u6765\u53bb\u91cd\uff0c
3\u3001drop\u8001\u7684\u8868
4\u3001\u5c06\u65b0\u8868\u6539\u540drename\u6210\u8001\u8868\u3002<\/p>\n\n\n\n
\u6b64\u65b9\u6cd5\u9002\u5408
1\u3001\u6781\u5c11\u91cf\u6570\u636e<\/span>\uff0c\u6bd4\u5982\u51e0\u767e\u884c\uff0c\u51e0\u73a9\u884c\u7ea7\u522b\u7684\u914d\u7f6e\u8868\uff0c\u7ef4\u5ea6\u8868\u7b49\uff1b
2\u3001\u5927\u91cf\u91cd\u590d\u6570\u636e\uff0c\u6bd4\u5982\u8d85\u8fc730%\u7684\u91cd\u590d\u6570\u636e\u3002<\/p>\n\n\n\n\u6570\u636e\u91cf\u5c11\uff0c\u53ef\u4ee5\u5728\u51e0\u79d2\u5185\u5904\u7406\u5b8c\u6210\u3002\u540c\u65f6\u8868\u6570\u636e\u53d8\u52a8\u9891\u7387\u53ef\u63a7\uff0c\u4e0d\u8981\u51fa\u73b0\u6570\u636e\u4e22\u5931<\/span>\uff08insert \u540e\u53ef\u80fd\u539f\u59cb\u8868\u53c8insert\u7684\u65b0\u6570\u636e\uff0c\u5207\u6362\u8868\u4f1a\u5bfc\u81f4\u6570\u636e\u4e22\u5931)\u7684\u524d\u63d0\u4e0b\u3002<\/p>\n\n\n\n\u5982\u6570\u636e\u53d8\u52a8\u4e0d\u53ef\u63a7\uff0c\u8bf7\u4e0d\u8981\u4f7f\u7528\u6b64\u65b9\u6848\u3002<\/p>\n\n\n\n
gbase> create table tc2 as select distinct * from tc1;\nQuery OK, 3 rows affected (Elapsed: 00:00:00.80)\n\ngbase> select * from tc2;\n+------+------+\n| id | name |\n+------+------+\n| 1 | 111 |\n| 2 | 222 |\n| 3 | 333 |\n+------+------+\n3 rows in set (Elapsed: 00:00:00.00)\n<\/code><\/pre>\n\n\n\n<\/p>\n\n\n\n
<\/span>\u4e34\u65f6\u8868\u6cd5<\/span><\/h2>\n\n\n\n\u6b64\u65b9\u6cd5\u9002\u5408\u5904\u7406\u6240\u6709\u573a\u666f\uff0c\u4f46\u5982\u679c\u7edd\u5927\u90e8\u5206\u90fd\u662f\u91cd\u590d\u6570\u636e\u5e93\uff0c\u6027\u80fd\u4e0a\u4e0d\u5982\u65b9\u6cd51\u7684\u91cd\u5efa\u65b9\u6848\u3002<\/p>\n\n\n\n
\u5904\u7406\u903b\u8f91\u5982\u4e0b\uff1a<\/p>\n\n\n\n
1\u3001\u5c06\u91cd\u590d\u6570\u636einsert\u5230\u4e00\u4e2a\u4e34\u65f6\u8868
2\u3001\u5c06\u91cd\u590d\u6570\u636e\u4ece\u539f\u59cb\u8868\u5220\u9664
3\u3001\u5c06\u4e34\u65f6\u8868\u6570\u636einsert\u5230\u6b63\u5f0f\u8868<\/p>\n\n\n\n
gbase> create table tc3 as select * from tc1 group by id,name having count(*) >1;\nQuery OK, 1 row affected (Elapsed: 00:00:00.65)\n\ngbase> select * from tc3;\n+------+------+\n| id | name |\n+------+------+\n| 1 | 111 |\n+------+------+\n1 row in set (Elapsed: 00:00:00.00)\n\ngbase> delete tc1 where id in (select id from tc3) ;\nQuery OK, 2 rows affected (Elapsed: 00:00:00.57)\n\ngbase> select * from tc1;\n+------+------+\n| id | name |\n+------+------+\n| 2 | 222 |\n| 3 | 333 |\n+------+------+\n2 rows in set (Elapsed: 00:00:00.00)\n\ngbase> insert into tc1 select * from tc3;\nQuery OK, 1 row affected (Elapsed: 00:00:00.49)\nRecords: 1 Duplicates: 0 Warnings: 0\n\ngbase> select * from tc1;\n+------+------+\n| id | name |\n+------+------+\n| 1 | 111 |\n| 2 | 222 |\n| 3 | 333 |\n+------+------+\n3 rows in set (Elapsed: 00:00:00.01)\n<\/code><\/pre>\n\n\n\n<\/span>\u590d\u5236\u8868\u7279\u6b8a\u65b9\u6848<\/span><\/h2>\n\n\n\n\u590d\u5236\u8868\uff0c\u56e0\u4e3a\u6bcf\u4e2a\u8282\u70b9\u7684\u6570\u636e\u5b8c\u5168\u4e00\u81f4\uff0c\u5305\u62ec\u987a\u5e8f\uff0c\u6240\u4ee5\u53ef\u4ee5\u7528rowid\u6765\u5220\u9664\u3002<\/p>\n\n\n\n
<\/span>\u590d\u5236\u8868\u6d4b\u8bd5\u6570\u636e<\/span><\/h3>\n\n\n\ngbase> create table tcc1 (id int, name varchar(100))replicated;\nQuery OK, 0 rows affected (Elapsed: 00:00:00.48)\n\ngbase> insert into tcc1 values(1,'1111');\nQuery OK, 1 row affected (Elapsed: 00:00:00.68)\n\ngbase> insert into tcc1 values(1,'1111');\nQuery OK, 1 row affected (Elapsed: 00:00:00.36)\n\ngbase> insert into tcc1 values(2,'2222');\nQuery OK, 1 row affected (Elapsed: 00:00:00.33)\n\ngbase> insert into tcc1 values(3,'3333');\nsQuery OK, 1 row affected (Elapsed: 00:00:00.48)\n\ngbase> select * from tcc1;\n+------+------+\n| id | name |\n+------+------+\n| 1 | 1111 |\n| 1 | 1111 |\n| 2 | 2222 |\n| 3 | 3333 |\n+------+------+\n4 rows in set (Elapsed: 00:00:00.00)\n\n<\/code><\/pre>\n\n\n\n