SELECT DISTINCT vs SELECT TheSELECT DISTINCTstatement is used when you want to return only unique (distinct) values in the result set. Whereas, a regularSELECTstatement without theDISTINCTkeyword retrieves all rows from the specified columns, including duplicate values. Let's look at an example. ...
ERROR 1062 (23000): Duplicate entry 'value' for key 'PRIMARY' 1. 解决方案: sql 复制下载 -- 使用INSERT IGNORE跳过重复记录 INSERT IGNORE INTO table_name VALUES (...); -- 使用ON DUPLICATE KEY UPDATE更新重复记录 INSERT INTO table_name VALUES (...) ON DUPLICATE KEY UPDATE column=VALUES(col...
TheSELECT DISTINCTstatement is used to return only distinct (different) values. ExampleGet your own SQL Server Select all the different countries from the "Customers" table: SELECTDISTINCTCountryFROMCustomers; Try it Yourself » Inside a table, a column often contains many duplicate values; and ...
values<foreachcollection="listData"item="item"index="index"separator=",">(#{item.id},#{item.agent},#{item.enterprise},#{item.operator},#{item.remark})</foreach>ON DUPLICATE KEY UPDATE id = values(id), agent = values(agent), enterprise = values(enterprise), operator = values(operator...
insert into test1(a,b,c) select a , b , c from test ON DUPLICATE KEY UPDATE b=b+values(b),c=c+values(c); 就会出现ERROR 1052 (23000): Column 'b' in field list is ambiguous 这是因为在上面的sql中,mysql不知道b到底是数据test 还是test1.所以就会出现上面错误。
SELECTCOUNT(*)AScFROMtable1ASt1JOINtable2ASt2ONCOALESCE(t1.string_field,'')=COALESCE(t2.string_field,'') 5. Not using temporary tables for complex queries SQL would be great if only we could debug queries. What if I told you can debug them!
write_rows :Duplicate entry(1062错误)主键冲突,主要表现为重复插入已经存在的记录; update_rows :Can't find record(1032错误),无法发现需要更新的行记录。 sql_slave_skip_counter 参数说明: 从官方解释知道,sql_slave_skip_counter以event 为单位 skip ,直到 skip 完第N个 event 所在的 event group 才停止。
SELECTDISTINCT*INTOduplicate_tableFROMoriginal_tableGROUPBYkey_valueHAVINGCOUNT(key_value) >1DELETEoriginal_tableWHEREkey_valueIN(SELECTkey_valueFROMduplicate_table)INSERToriginal_tableSELECT*FROMduplicate_tableDROPTABLEduplicate_table 此脚本按给定顺序执行以下操作: ...
CREATE TABLE TestBatch (ColA INT PRIMARY KEY, ColB CHAR(3)); GO INSERT INTO TestBatch VALUES (1, 'aaa'); INSERT INTO TestBatch VALUES (2, 'bbb'); INSERT INTO TestBatch VALUES (1, 'ccc'); -- Duplicate key error. GO SELECT * FROM TestBatch; -- Returns rows 1 ...
In the output, you will notice that only two rows are displayed. When you tweak the query and add the reference of both columns within theselectstatement, you get a count of matching rows with duplicate values. Instead of thecount(column)function, you must pass thecount(*)function to get...