How do you UNION a column in SQL?

Using the SQL UNION Operator Use the ALL keyword with UNION to allow duplicate values. The column names in the result-set of a UNION are usually equal to the column names in the first SELECT statement in the UNION. Within UNION each SELECT statement must have the same columns number.

Can you UNION 2 tables with different columns?

The columns of joining tables may be different in JOIN but in UNION the number of columns and order of columns of all queries must be same. 2.)

How do I merge two columns of string in SQL?

SQL Server CONCAT() Function

  1. Add two strings together: SELECT CONCAT(‘W3Schools’, ‘.com’);
  2. Add 3 strings together: SELECT CONCAT(‘SQL’, ‘ is’, ‘ fun!’ );
  3. Add strings together (separate each string with a space character): SELECT CONCAT(‘SQL’, ‘ ‘, ‘is’, ‘ ‘, ‘fun!’ );

How does UNION work in SQL?

The Union operator combines the results of two or more queries into a single result set that includes all the rows that belong to all queries in the Union. In simple terms, it combines the two or more row sets and keeps duplicates.

How do you Union a column?

SQL UNION Operator

  1. Every SELECT statement within UNION must have the same number of columns.
  2. The columns must also have similar data types.
  3. The columns in every SELECT statement must also be in the same order.

Does Union in SQL remove duplicates?

The SQL UNION ALL operator is used to combine the result sets of 2 or more SELECT statements. It does not remove duplicate rows between the various SELECT statements (all rows are returned). Each SELECT statement within the UNION ALL must have the same number of fields in the result sets with similar data types.

How do I concatenate three columns in SQL?

  1. CONCAT. This function is used to concatenate multiple columns or strings into a single one.
  2. CONCAT_WS. The CONCAT_WS() function not only adds multiple string values and makes them a single string value.
  3. Using them in WHERE CLAUSE. You can use both of them in WHERE CLAUSE for selection based on condition.
  4. Conclusion.

Does SQL union remove duplicates?

SQL Union All Operator Overview The SQL Union All operator combines the result of two or more Select statement similar to a SQL Union operator with a difference. The only difference is that it does not remove any duplicate rows from the output of the Select statement.

How do I merge two SQL queries?


  1. To combine two or more SELECT statements to form a single result table, use the set operators: UNION, EXCEPT or INTERSECT.
  2. To keep all duplicate rows when combining result tables, specify the ALL keyword with the set operator clause.

What is Union select in SQL?

SQL UNION. The SQL UNION clause merges the results of two or more SELECT SQL queries into one result set. When using SQL UNION, all the SQL expressions participating in the UNION must have the same structure (they have to have the same number of columns and same or compatible data types).

How do you select column in SQL?

Selecting All Columns in a Table Use an asterisk in the SELECT clause to select all columns in a table. The following example selects all columns in the SQL.USCITYCOORDS table, which contains latitude and longitude values for U.S. cities: To select a specific column in a table, list the name of the column in the SELECT clause.

What is the SQL UNION command?

Union is an SQL command that combines the results of two or more select statements without returning any duplicate rows. Union All is an SQL command that combines the result of two or more select statements including duplicate rows.

What is a SQL Server Union?

SQL Server UNION is one of the set operations that allows you to combine results of two SELECT statements into a single result set which includes all the rows that belongs to the SELECT statements in the union. The following illustrates the syntax of the SQL Server UNION: The following are requirements for the queries in the syntax above: