SQL Questions

SELECT *FROM Employees WHERE EmpName like ‘M%’.

SQL Server runs on port 1433. It can be changed from the Network Utility TCP/IP properties.

Properties of Sub-Query

- A sub-query must be enclosed in the parenthesis.

- A sub-query must be put in the right hand of the comparison operator, and

- A sub-query cannot contain an ORDER-BY clause.

- A query can contain more than one sub-query.

Types of Sub-Query

- Single-row sub-query, where the sub-query returns only one row.

- Multiple-row sub-query, where the sub-query returns multiple rows,. and

- Multiple column sub-query, where the sub-query returns multiple columns

SELECT "column_name"

FROM "table_name"

WHERE "column_name" IS NULL.

Use the DBMS_OUTPUT package. Another possible method is to use the SHOW ERROR command.

SQL JOIN allows access to records of other table based on the given conditions between two tables.

Ex: If we are provided with the department ID of each employee, then we can use the department ID of the employee table to merge with the department ID of the department table to access department names.

UNION operation allows addition of 2 similar data sets to create a resulting set that contains all the data from the source data sets.

Ex: If we are provided with 2 employee tables of the same structure, we can UNION them to create a singular result that will contain all employee from both the table.