Jennifer Nicholas has Published 363 Answers

What do you mean by Scope of variables inside MySQL stored procedure?

Jennifer Nicholas
Jennifer Nicholas
Published on 21-Feb-2018 15:39:07
Suppose if we declare a variable inside a BEGIN/END block then the scope of this variable would be in this particular block. We can also declare a variable with the same name inside another BEGIN/END block which will be totally legal but its scope would be inside its BEGIN/END block. ... Read More

What is stored procedure and how can we create MySQL stored procedures?

Jennifer Nicholas
Jennifer Nicholas
Published on 21-Feb-2018 11:51:58
Stored procedure, in the context of regular computing language, may be defined as a subroutine like a subprogram that is stored in a database. In the context of MySQL, it is a segment of declarative SQL statements stored inside the database catalog. Before writing stored procedures in MySQL, we must ... Read More

What is the use of CHECK TABLE statement in maintaining the MySQL tables?

Jennifer Nicholas
Jennifer Nicholas
Published on 20-Feb-2018 18:04:17
There may be something wrong which can happen to the database server e.g., the server was shutdown unexpectedly, error while writing data to the hard disk, etc. These situations could make the database operate incorrectly and in the worst case, it can be crashed.With the help of CHECK TABLE statement ... Read More

How DIFFERENCES between tables can be implemented with the help of MySQL joins?

Jennifer Nicholas
Jennifer Nicholas
Published on 20-Feb-2018 16:29:56
We can get the differences between the tables by unioning exclusion joins from 1st table to 2nd table and from 2nd table to 1st table. To understand it, we are taking the example of following two tables −mysql> Select * from value1; +-----+-----+ | i   | j   | ... Read More

How can we take a backup of a particular table from a database by using mysqldump client program?

Jennifer Nicholas
Jennifer Nicholas
Published on 20-Feb-2018 14:47:26
By using mysql dump client program we can take the backup of a particular table from the 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 ... Read More

Why should we not store a number into a MySQL ENUM column?

Jennifer Nicholas
Jennifer Nicholas
Published on 20-Feb-2018 11:13:53
MySQL stores ENUM values internally as integer keys (index numbers) to reference ENUM members. The main reason for not storing the integer values in ENUM column is that it is very obvious that MySQL ends up referencing the index instead of the value and vice-versa.ExampleFollowing example can clarify it −mysql> ... Read More

What would be the effect on the output of MySQL LAST_INSERT_ID() function in the case on multiple-row insert?

Jennifer Nicholas
Jennifer Nicholas
Published on 19-Feb-2018 17:39:20
As we know that MySQL LAST_INSERT_ID() function returns the latest generated sequence number but in case of multiple row-insert it would return the sequence number generated by the foremost inserted row.Examplemysql> Insert into Student(Name) values('Ram'), ('Mohan'), ('Aryan'); Query OK, 3 rows affected (0.03 sec) Records: 3 Duplicates: 0 Warnings: 0The query ... Read More

How can I store the fixed length string as well as variable length string in the same MySQL table?

Jennifer Nicholas
Jennifer Nicholas
Published on 19-Feb-2018 16:46:49
As we know that CHAR is used to store fixed length string and VARCHAR is used to store variable length strings. Hence we can store a fixed length as well as variable length string in the same table by declaring a column as CHAR and other as VARCHAR.Examplemysql> Create Table ... Read More

How to get the total number of seconds from a MySQL DATETIME instance?

Jennifer Nicholas
Jennifer Nicholas
Published on 19-Feb-2018 14:31:25
The MySQL DateTime instance can be converted into seconds with the help of UNIX_TIMESTAMP() function in the following way −mysql> Select UNIX_TIMESTAMP('2017-05-15 04:05:30') AS 'NUMBER OF SECONDS'; +-------------------+ | NUMBER OF SECONDS | +-------------------+ |        1494801330 | +-------------------+ 1 row in set (0.00 sec)Above query will ... Read More

What is the way to find business days between two specified dates in MySQL?

Jennifer Nicholas
Jennifer Nicholas
Published on 19-Feb-2018 11:08:07
With the help of DATEDIFF(expr1, expr2) we can find the business days between two specified dates.For example, if we want to find business days between ‘2017-05-27’ and ‘2017-05-23’ then following would be MySQL query −mysql> Select DATEDIFF('2017-05-27', '2017-05-23') AS 'Total Business Days'; +----------------------+ | Total Business Days  | +----------------------+ | ... Read More
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