SQL Advance Tutorial

SQL GETDATE()

SQL GETDATE() function returns the current date and time.

SQL CHARINDEX()

SQL CHARINDEX() function searches for a substring inside a string starting from a specified location.

SQL SUBSTRING()

SQL SUBSTRING()functions extracts a substring with a specified length starting from a location in an input string.

SQL DATALENGTH Function

SQL DATALENGTH() function is used to return the number of bytes used to represent a given string.

SQL Server RTRIM()

SQL Server RTRIM() function is used to trim trailing characters from a character string.

SQL Server LTRIM()

SQL Server LTRIM() function is used to trim leading characters from a character string.

SQL SERVER REPLACE

SQL REPLACE() function is used to replace all occurrences of a substring in a string with a new substring .

SQL LOWER()

SQL LOWER() function converts all the characters in a string into lowercase.

SQL LEN()

SQL LEN() function is used to count the number or length of character in given string. It returns integer value always and null for empty string.

SQL EOMONTH()

SQL EOMONTH() function is a date function , it returns the last day of the month of a specified date, with an optional offset.

SQL Server DELETE

SQL delete statement is used to delete records from table based on specific conditions which are passed in where clause.

SQL SERVER INSERT

SQL insert statement is used to insert a new records in table.

SQL SERVER UPDATE

SQL UPDATE Statement is used to modify an existing
records in table .

SQL TRUNCATE TABLE

SQL TRUNCATE TABLE statement is used to delete complete data from an existing table. It is similar to a delete statement without a WHERE clause.

Primary Key VS Composite Key?

A PRIMARY KEY constraint uniquely identifies each record in a table .

A COMPOSITE KEY is a combination of two or more columns in a table that can be used to uniquely identify each row in the table when the columns are combined uniqueness is guaranteed, but when it taken individually it does not guarantee uniqueness.

SQL DROP TABLE

SQL DROP TABLE statement is used to delete the table from database.

SQL ALTER TABLE

SQL ALTER TABLE statement is used to modify the data type of a column , add a new column ,delete an old column from table and add a new constraints and remove an existing constraints on table.