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Aggregate Functions SQL aggregate functions return a single value, calculated from values in a column. Useful aggregate functions: Function Description AVG() Returns the average value COUNT() [...]

Information Functions CONNECTION_ID() Returns the connection ID (thread ID) for the connection. Every connection has an ID that is unique among the set of currently connected clients. [...]

Date and Time Functions CURDATE(),CURRENT_DATE, CURRENT_DATE() Returns the current date as a value in ‘YYYY-MM-DD’ or YYYYMMDD format, depending on whether the function is used in a [...]

MySQL String functions UPPER(), UCASE() Returns the string with all characters changed to uppercase. LOWER(), LCASE() Returns the string with all characters changed to lowercase. CHAR_LENGTH(str) [...]

A subquery is a SELECT statement within another statement. Here is an example of a subquery: SELECT * FROM t1 WHERE column1 = (SELECT column1 FROM t2); The main advantages of subqueries are: They [...]

DROP INDEX index_name ON tbl_name DROP INDEX drops the index named index_name from the table tbl_name. After deleting the index on ‘gender’ column, the performance enhancement is lost.

How to create a Servlet with Eclipse and Tomcat

Environment Used JDK 6 (Java SE 6) Eclipse Indigo IDE for Java EE Developers (3.7.1) Apache Tomcat 6.x Java EE 5 API (Servlet 2.5) [Optional] For monitoring and analyzing HTTP headers between the [...]

Environment Used JDK 6 (Java SE 6) (To install JDK – Windows , Ubuntu) Eclipse Indigo IDE for Java EE Developers (3.7.1) (To install Eclipse, refer this page) Apache Tomcat 6.x (To install [...]

Environment Used JDK 6 (Java SE 6) (To install JDK – Windows , Ubuntu) Eclipse Indigo IDE for Java EE Developers (3.7.1) (To install Eclipse, refer this page) Apache Tomcat 6.x (To install [...]