Database Articles - Page 631 of 671

Suppose if we want to restore a file that has been created by mysqldump then we can restore in an existing database or in a new database after creating it. Then with the help of SOURCE statement, we can restore it. We can illustrate it by an example:ExampleIn this example, we are restoring the table named student_info.sql which has been dumped. It was basically in the database name ‘query’. Now we will restore it into a database named ‘tutorials’.mysql> Use Tutorials; Database changed mysql> SOURCE student_info.sql; Query OK, 0 rows affected (0.00 sec) Query OK, 0 rows affected ... Read More

We can check whether a string of specified pattern is not present within another string by using NOT LIKE operator along with wildcard characters.SyntaxNOT LIKE specific_patternSpecific_pattern is the pattern of string we do not want to find out within another string.ExampleSuppose we have a table named ‘student’ having names of the students and we want to get the details of all those students which are not having a pattern of string ‘av’ within their names. It can be done with the help of following MySQL query:mysql> Select * from Student WHERE name NOT LIKE '%av%'; +------+---------+---------+----------+--------------------+ | Id   ... Read More

As we know that NOT LIKE operator is used along with WILDCARD characters for not getting the string having specified string. Basically, WILDCARD is the characters that help search data matching complex criteria. Followings are the types of wildcard which can be used in conjunction with NOT LIKE operator:% - The PercentageThe ‘%’ wildcard is used to specify a pattern of 0, 1 or more characters. A basic syntax for using % wildcard with NOT LIKE operator is as follows:Select Statement…Where column_name NOT LIKE ‘X%’Here X is any specified starting pattern such as the single character of more and % matches ... Read More

We have seen the MySQL SELECT command to fetch data from the MySQL table. We can also use a conditional clause called as the WHERE clause to select the required records.A WHERE clause with the ‘equal to’ sign (=) works fine where we want to do an exact match. Like if "tutorial_author = 'Sanjay'". But there may be a requirement where we want to filter out all the results where the tutorial_author name should contain "jay". This can be handled using MySQL LIKE operator along with the WHERE clause.If the MySQL LIKE operator is used without a wildcard character, the ... Read More

By using mysql dump client program we can take the backup of multiple databases into a file having the extension ‘.sql’. It can be understood with the help of the following example −ExampleIn this example, with the help of mysql dump client program, we are taking the backup of two databases named ‘tutorials’ and ‘query1’ in a file named ‘tutorials_query1.sql’. The following command will do this −C:\mysql\bin>mysqldump -u root --databases tutorials query1 > tutorials_query1.sqlThe above command will create a file named tutorials_query1.sql which have the dump information of both the databases named tutorials and query1.Read More

By using mysqldump client program we can take the backup of a database into a file having the extension ‘.sql’. it can be understood with the help of following example −ExampleIn this example, with the help of mysqldump client program, we are taking the backup of a database named ‘tutorials’ in a file named ‘tutorials.sql’. The following command will do this −C:\mysql\bin>mysqldump -u root tutorials > tutorials.sqlThe above command will create a file named ‘turorials.sql’ in the bin folder of MySQL. This file will contain drop table, create a table and insert command for all the tables in the tutorials ... Read More

We can apply any of the functions like SUBSTRING(), MID() or SUBSTR() to extract a substring from the value of a column. In this case, we must have to provide the name of the column as the first argument of the function i.e. at the place of string we have to give the name of the column. Following example will demonstrate it.ExampleSuppose we want to extract a substring from the ‘Name’ column of ‘Student’ table then it can be done by using the different functions as follows −mysql> Select name, SUBSTR(name, 2, 4) from student; +---------+------------------+ | name    | ... Read More

Actually for using MySQL TRIM() function we must have to know the string which we want to trim from the original string. This becomes the major drawback of TRIM() in the cases where we want to trim the strings having different values. For example, suppose we want to get the output after trimming the last two characters from the strings but every string is having different characters at last two places.Examplemysql> Select * from Employee; +------+----------------+------------+-----------------+ | Id   | Name           | Address    | Department      | +------+----------------+------------+-----------------+ | 100  | Raman ... Read More

MySQL SUBSTRING() function can be used to extract a substring from a string. Basically SUBSTRING() returns a substring with a given length from a string starting at a specific position. It has various forms as follows −SUBSTRING(str, pos)SUBSTRING(str FROM pos)SUBSTRING(str, pos, len)SUBSTRING(str FROM pos FOR len)The forms without a len argument return a substring from string str starting at position pos. The forms with a len argument return a substring len characters long from string str, starting at position pos. The forms that use FROM are the standard MySQL syntax. It is also possible to use a negative value for ... Read More

By default MySQL will assume the argument BOTH if the 1st argument is not specified in TRIM() function. Following example will demonstrate it.Examplemysql> SELECT TRIM('A' FROM 'ABCDAEFGAA'); +-----------------------------+ | TRIM('A' FROM 'ABCDAEFGAA') | +-----------------------------+ | BCDAEFG                     | +-----------------------------+ 1 row in set (0.00 sec)The above result set shows that when we did not specify 1st argument then MySQL returns the output by assuming BOTH as the 1st argument of TRIM() function.