You can use this statement to combine both tables using union with a WHERE clause SELECT name FROM students You can use this statement to combine both tables using union with a GROUP BY SELECT COUNT(id), city You can use this statement to combine both tables using union with an ORDER BY. You can use the following formats to combine both tables students & employees – UNION with ORDER BY The students’ table contains the following values – Id int(10) PRIMARY KEY NOT NULL AUTO_INCREMENT, Here the query to create students table – CREATE TABLE students Now, We will get a new table by combining these tables – Suppose that we have two tables like students & employees that have four columns like, name & city. Each table may have distinct values, duplicate values or combination of both valuesįor your better understanding, You will have to read the example in the next step UNION – Example.The number of records in each table may be the same or different.Corresponding column names of each table may be the same or different.The number of columns in each table may be the same or different.Datatypes of the corresponding column in each table must be the same.UNION is used to combine more than one table into a single table with distinct values using SELECT statements. But remember that you must declare a UNION operator between two select statements. You can combine more tables with more columns as your requirements. I have created this syntax for combining the three tables with four columns. The above syntax is only for understanding how to combine more than two tables. SELECT column_name1, coumn_name2, column3, column_name4 FROM table3 SELECT column_name1, coumn_name2, column3, column_name4 FROM table2 It has the following syntax – SELECT column_name1, coumn_name2, column3, column_name4 FROM table1 Corresponding columns of each select statement must be with the same expression and aggregate function.Data Types of corresponding columns of each SELECT statement must be the same.All the columns in each SELECT statement must be in the same order.Each SELECT Settlement must be declared with the same number of columns.UNION operation must satisfy the following rules Even It selects only unique values and leaves duplicate values. It combines result sets of more than one select statement into a single result set. UNION is a set operator in the SQL server. So, continue reading this complete tutorial. Now, you will know more about it in detail from the next steps. The above example is enough to understand the UNION concept. Because UNION always gives result sets with distinct values by combining more than one set. Both sets have two duplicate/ common values 3, 4. When we combine both sets, we will get a final result_set with distinct values like 1, 2, 3, 4, 5, 6, 7, 8. set_1 has four values like 1, 2, 3, and set_2 has six values like 3, 4, 5, 6, 7, 8. This tutorial will be also very helpful to get more information related to it such as union command, syntax, usage & steps to use union so on.įor a better understanding, We have taken two sets like set_1 & set_2 are shown in the figure below. In his tutorial, you will know the complete overview of SQL Union with an Example.
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