-- MySQL、SQL Server 等INSERT INTO test(id) VALUES (1),(2),(3); -- OracleINSERT INTO test(id)(SELECT 1 AS id FROM DUALUNION ALLSELECT 2 FROM DUALUNION ALLSELECT 3 FROM DUAL); 我们通过一个 INSERT 语句插入了 3 条记录,或者说是插入了一个包含 3 条记录的关系表。因为,UNION ALL 返回...
What's UNION? Union allows us, developers, to combine all rows in two union-compatible tables or two sets of rows into a single result set. In addition, the result set includes all the rows belonging to all the queries in the UNION. When using UNION, the order of tables doesn't matte...
2019-12-11 17:33 −What is the difference between UNION and UNION ALL? UNION removes duplicate records (where all columns in the results are the same), UNION ALL does no... ChuckLu 0 297 SQL——SQL别名、UNION和SELECT INTO 2019-12-13 15:47 −Alias(别名) - 为列名称和表名称指定别...
UNION UNIONis one of the four basic ‘set operators’in SQL. The UNION operator is used to combine the results of two or more SELECT Statement queries into a single result-set,excluding duplicate values.Using the UNION operator willnotallow duplicate values in the results. (See UNION ALL for...
What is SQL? Обзор How to find duplicate values in a SQL Table How to show all table servers in SQL Master Regex in SQL Efficient column updates in SQL Visualizing SQL joins Indexing essentials in SQL Single quote, double quote, and backticks in MySQL queries Null replace...
What is the difference between UNION and UNION ALL? UNIONremoves duplicate rows. UNION ALL doesnotremove duplicate rows. Syntax The syntax for the UNION ALL operator in SQL is: SELECT expression1, expression2, ... expression_n FROM tables [WHERE conditions] UNION ALL SELECT expression1, expres...
UNION ALL can very well be a big speedup for you. What if you already know that your data does not contain duplicates in either row, or what if you don't care about duplicates? In either case, UNION ALL is for you. Further, there may be other ways you can avoid the duplicates in...
Learn More:What is the Difference Between a Join and a Union >> Combine Table Rows Using SQL UNION The Union operator returns rows from both tables. Use UNION to return a distinct list of values. Use UNION ALL to return distinct rows. SQL UNION for sorting results from two separate querie...
In SQL, the Union operator is used to combining the output from multiple SELECT statements. The result-sets of SELECT statements should be the same number of columns, similar data types of columns, and columns should be in the same order. ...
CREATE PROC What_DB_is_this AS SELECT DB_NAME() AS ThisDB; 使用后列语句调用存储过程:EXEC What_DB_is_this;稍微复杂一点的情况是提供一个输入参数以使过程更灵活。 例如:SQL 复制 CREATE PROC What_DB_is_that @ID INT AS SELECT DB_NAME(@ID) AS ThatDB; 调用过程时,请提供数据库 ID 号。