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How to delete index in MySql

How to delete index in MySql, first you need to know the exact name of the INDEX (Unique key in this case) to delete or update it. INDEX names are usually same as column names. In case of more than one INDEX applied on a column, MySQL automatically suffixes numbering to the column names to create unique INDEX names. For ...

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Drop or Delete Table – SQL

Drop or Delete Table – SQL statement is used to remove a table definition and all data, indexes, triggers, constraints, and permission specifications for that table. NOTE: You have to be careful while using this command because once a table is deleted then all the information available in the table would also be lost forever. Syntax: Basic syntax of DROP ...

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NULL Values – SQL

NULL Values – SQL is the term used to represent a missing value. A NULL value in a table is a value in a field that appears to be blank. A field with a NULL value is a field with no value. It is very important to understand that a NULL value is different than a zero value or a field ...

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Useful Functions SQL

Useful Functions SQL has many built-in functions for performing processing on string or numeric data. Following is the list of all useful SQL built-in functions: SQL COUNT Function – The SQL COUNT aggregate function is used to count the number of rows in a database table. SQL MAX Function – The SQL MAX aggregate function allows us to select the ...

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Insert Query Into Table – SQL

Insert Query Into Table – SQL Statement is used to add new rows of data to a table in the database. Syntax: There are two basic syntaxes of INSERT INTO statement as follows: INSERT INTO TABLE_NAME (column1, column2, column3,...columnN)] VALUES (value1, value2, value3,...valueN); Here, column1, column2,…columnN are the names of the columns in the table into which you want to ...

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Alias Syntax – SQL

Alias Syntax – SQL — You can rename a table or a column temporarily by giving another name known as alias. The use of table aliases means to rename a table in a particular SQL statement. The renaming is a temporary change and the actual table name does not change in the database. The column aliases are used to rename ...

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COUNT Function SQL

COUNT Function SQL is the simplest function and very useful in counting the number of records, which are expected to be returned by a SELECT statement. To understand COUNT function, consider an employee_tbl table, which is having the following records: SQL> SELECT * FROM employee_tbl; +------+------+------------+--------------------+ | id | name | work_date | daily_typing_pages | +------+------+------------+--------------------+ | 1 | John ...

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Select Query – SQL

Select Query – SQL statement is used to fetch the data from a database table which returns data in the form of result table. These result tables are called result-sets. Syntax: The basic syntax of SELECT statement is as follows: SELECT column1, column2, columnN FROM table_name; Here, column1, column2…are the fields of a table whose values you want to fetch. ...

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Indexes – SQL

Indexes are special lookup tables that the database search engine can use to speed up data retrieval. Simply put, an index is a pointer to data in a table. An index in a database is very similar to an index in the back of a book. For example, if you want to reference all pages in a book that discuss ...

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MAX Function SQL

MAX Function SQL is used to find out the record with maximum value among a record set. To understand MAX function, consider an employee_tbl table, which is having the following records: SQL> SELECT * FROM employee_tbl; +------+------+------------+--------------------+ | id | name | work_date | daily_typing_pages | +------+------+------------+--------------------+ | 1 | John | 2007-01-24 | 250 | | 2 | Ram ...

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