SQL Questions

LIKE is a keyword that is used in the WHERE clause. Basically, LIKE allows us to do a search based operation on a pattern rather than specifying exactly what is desired (as in IN) or spell out a range (as in BETWEEN).

The syntax is as follows:
SELECT "column_name"
FROM "table_name"
WHERE "column_name" LIKE {PATTERN}

{PATTERN} often consists of wildcards.

In SQL, there are two wildcards:


% (percent sign) represents zero, one, or more characters.

_ (underscore) represents exactly one character.

More :: Certification Questions on SQL

A subquery in an SQL SELECT statement is enclosed in parenthesis (...).

SELECT COUNT(*), sex from Employees  WHERE  DOB BETWEEN ‘01/01/1960 ' AND ‘31/12/1975’  GROUP BY sex;

The Data Definition Language (DDL) is used to manage table and index structure.

CREATE,

ALTER,

RENAME,

DROP and

TRUNCATE

statements are the names of few data definition elements.

The comparison operator that is used in SQL is '='. Comparison operators test whether two expressions are the same. Comparison operators can be used on all expressions except expressions of the text, ntext, or image data types.

SQL has IsDate() function which is used to check passed value is date or not of specified format ,it returns 1(true) or 0(false) accordingly.

SELECT  ISDATE('1/08/13') AS "MM/DD/YY";

It will return 0 because passed date is not in correct format.

SELECT  * from Employees  WHERE  upper(EmpName) like upper('joe%');

The built in function called GetDate() returns the time stamp.