TechOnespot

 MySQL SQL Revision Tour  SUMMARY The basic elements of MySQL SQL are: literals, datatypes, nulls and comments. Literals are fixed data values. Data types of MySQL SQL include: NUMERIC (INT, TINYINT, SMALLINT, MEDIUMINT, BIGINT, FLOAT(M, D), DOUBLE(M. D) AND DECIMAL(M, D), DATE and TIME (DATE, DATETIME, TIMESTAMP, TIME and YEAR(M) and STRING (CHAR(M). VARCHAR(M), BLOB or TEXT, TINYBLOB or TINYTEXT, MEDIUMBLOB or MEDIUMTEXT and ENUM).  Column having no value is said to have NULL value. The SELECT command of SQL lets you make queries on the database.  The DISTINCT keyword eliminates redundant data. To perform calculations, the expressions can be written along with SELECT without specifying any table name. A small work table Dummy can be used for making simple calculations. The curdate pseudo-column returns the current system date. The WHERE clause is used to select specific rows. The logical operators OR (II), AND (&&) and NOT (!) are used to connect search conditions in the WHER