Can UNION work with different columns?

Using UNION on Multiple Fields We can apply UNION on multiple columns and can also order the results using the ORDER BY operator in the end. This will result in the following: The result is sorted according to the “Dept_ID.” We can also filter the rows being retrieved by each SELECT statement.

Can UNION be done on same table?

SQL joins allow you to combine two datasets side-by-side, but UNION allows you to stack one dataset on top of the other. Put differently, UNION allows you to write two separate SELECT statements, and to have the results of one statement display in the same table as the results from the other statement.

Does UNION query include same number of columns?

JOIN operations do NOT require the same number of columns be selected in both tables. UNION operations are different that joins. Think of it as two separate lists of data that can be “pasted” together in one big block. You can’t have columns that don’t match.

How do I restrict a column in Oracle?

Check Constraint Examples The following statement creates a divisions table and defines a check constraint in each column of the table: CREATE TABLE divisions (div_no NUMBER CONSTRAINT check_divno CHECK (div_no BETWEEN 10 AND 99) DISABLE, div_name VARCHAR2(9) CONSTRAINT check_divname CHECK (div_name = UPPER(div_name)) …

How do I UNION a different column in SQL?

Try this:

  1. select col1, col2, col3,null as col5 ,……from table1.
  2. union.
  3. select col1, col2, col3, col5 …. from table2.

How do I join two tables with different column names?

Simply put, JOINs combine data by appending the columns from one table alongside the columns from another table. In contrast, UNIONs combine data by appending the rows alongside the rows from another table. Note the following when using UNION in SQL: All SELECT statements should list the same number of columns.

What is the difference between UNION and UNION all?

The UNION ALL command is equal to the UNION command, except that UNION ALL selects all values. The difference between Union and Union all is that Union all will not eliminate duplicate rows, instead it just pulls all rows from all tables fitting your query specifics and combines them into a table.

Does UNION require same column names?

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. The columns must have analogous data types. In each SELECT statement, the columns must be in the same order.

How do you take a UNION of two columns in SQL?

The UNION operator is used to combine the result-set of two or more SELECT statements.

  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.

How do I restrict a column value in SQL?

The CHECK constraint is used to limit the value range that can be placed in a column. If you define a CHECK constraint on a column it will allow only certain values for this column. If you define a CHECK constraint on a table it can limit the values in certain columns based on values in other columns in the row.

How do I put two constraints on a single column?

We can create a table with more than one constraint in its columns….

  1. Primary Key constraint – Sr_no in Fd_master where pk is userdefined name given to Primary key.
  2. Foreign Key constraint – Branch_no in Fd_master where fk is name of foreign key that references branch table.
  3. Check constraint –