Is there a DUAL table in db2?
Is there a DUAL table in db2?
The DB2® data server resolves any unqualified reference to the DUAL table as a built-in view that returns one row and one column that is named DUMMY, whose value is ‘X’.
How do I run a select query in db2?
Examples
- Execute a dummy SQL query: zowe db2 execute sql –query “SELECT ‘Hello World’ FROM SYSIBM. SYSDUMMY1” Copy.
- Retrieve the employees table and total number of rows: zowe db2 execute sql -q “SELECT * FROM SAMPLE. EMP; SELECT COUNT(*) AS TOTAL FROM SAMPLE. EMP” Copy.
- Execute a file with SQL statements:
What is the meaning of <> in db2?
Comparison operators
| Comparison operator | Description |
|---|---|
| < | Less than |
| > | Greater than |
| <= or ¬> or !> | Less than or equal to (or not greater than) |
| > = or ¬< or !< | Greater than or equal to (or not less than) |
What is the use of Sysibm SYSDUMMY1?
It is used for SQL statements in which a table reference is required, but the contents of the table are not important. The schema is SYSIBM. Unlike the other catalog tables, which reside in Unicode table spaces, SYSIBM. SYSDUMMY1 resides in table space SYSEBCDC, which is an EBCDIC table space.
What is the use of DUAL table in SQL?
Selecting from the DUAL table is useful for computing a constant expression with the SELECT statement. Because DUAL has only one row, the constant is returned only once. Several other databases, including MS SQL Server, MySQL, PostgreSQL and SQLite, allows the omitting of FROM clause.
How do I join two tables in Db2?
- Inner join. You can use an inner join in a SELECT statement to retrieve only the rows that satisfy the join conditions on every specified table.
- Left outer join. The LEFT OUTER JOIN clause lists rows from the left table even if there are no matching rows on right table.
- Right outer join.
- Full outer join.
What can you SELECT from dual?
Because DUAL has only one row, the constant is returned only once. Alternatively, you can select a constant, pseudocolumn, or expression from any table, but the value will be returned as many times as there are rows in the table.
What does SELECT * from dual return?
When you select an expression say 1 from a table (can be dual or any other table), it will return the expression depending on the number of rows in the table. Eg:- Select 1 from dual; returns 1 as there is only one record in dual.
