Mysql union all select

It returns all rows from the query and it does not remove duplicate rows between the various SELECT statements. UNION is used to combine the result from multiple SELECT statements into a single result set. The column names from the first SELECT statement are used as the column names for the returned. The default characteristic of UNION is, to remove the duplicate rows from the result. The DISTINCT keyword which is optional does not make any effect, because, by default, it specifies duplicate-row removal.

The number of columns and data types in the SELECT statements must be the same in order for the UNION command to work. The DISTINCT clause is used to eliminate duplicate values from the UNION query result set. The UNION ALL command combines the result set of two or more SELECT statements (allows duplicate values). What is the difference between UNION and. Also duplicate records are returned as UNION ALL returns all records from each result set and does not remove duplicate.

If you use UNION ALL , the entire result set from the second SELECT statement is appended to the first SELECT statement. In this case, there could be duplicate records in the unioned result set. It does not remove duplicate rows between the various SELECT statements ( all rows are returned). How to union tables into a new table in mysql ? SELECT name, description, price FROM products WHERE category= AND 1=UNION SELECT username, passwor FROM members Just a quick remark about the last example.

An always false condition was added to the WHERE clause of the original query before the UNION operator. Get table name from union query ? I have the same problem. Im glad that someone has my same problem. It was driving me crazy thinking that was some problem of access. I tested to union just two Selects, and running the entire query on mysql , etc.

Select and one Union ) in msaccess using myodbc to connect to. We use the UNION ALL when we want to get all the values and not the distinct values. All the SELECT queries must select the same number of columns. The columns selected in the queries must contain the same type of data.

The result set contains all the rows from the first query, followed by all the rows from the second query, and so on. It combines the both SELECT statement result sets and return as it is. The UNION keyword is used to connect two or more SELECT statements but the result of each select statement must have the same number of columns, and the data type of the corresponding columns in each table must be compatible. The Union Clause is used to combine two separate select statements and produce the result set as a union of both the select statements. NOTE: The fields to be used in both the select statements must be in same order, same number and same data type.

Both the UNION and UNION ALL operators achieve the common goal of combining the of two or more SELECT statements. As such, each query within the UNION must select the same number of fields with compatible data types - i. Combine , sort, remove duplicates and return the set. Queries with UNION can be accelerated in two ways. Switch to UNION ALL or try to push ORDER BY, LIMIT and WHERE conditions inside each subquery.

The above command will show all the user and their password for the users table of the mysql schema. The mysql schema controls all the authentication and authorization for all the databases. It turns out that both UNION and UNION ALL can create internal temporary tables to get the job done. I suppose it’s not that.

Union or Union All operator requires those two conditions to be meet: 1. There must be same number of expressions in both SELECT statements. Unlike the UNION operator, the INTERSECT operator returns the intersection between two circles. Note that the SQL standard has three set operators that include UNION , INTERSECT, and MINUS.

However, you can emulate the INTERSECT operator. MySQL Database Forums on Bytes.