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MySQLi Articles
Page 108 of 341
What MySQL returns on running the INSERT INTO statement without giving the column name and values both?
When we run the INSERT INTO statement without giving the columns name/s and values both then MySQL will store NULL as the value of the column/s of table. Consider the example given below in which we have created a table ‘Student’ with the following query −mysql> Create table Student(RollNO INT, Name Varchar(20), Class Varchar(15)); Query OK, 0 rows affected (0.17 sec)Now, we can run INSERT INTO statement without giving the columns name/s and values both as follows −mysql> Insert into Student() Values(); Query OK, 1 row affected (0.02 sec)We can see from the query below MySQL stores NULL as the ...
Read MoreHow can we change the default MySQL database to the given database?
Suppose currently we are using a tutorial database so it would be the default MySQL database for subsequent queries. Now, with the help of USE db_name statement, we can change the default database to other given database subsequent queries.mysql> USE Sample Database changedThe database has been changed to Sample from the tutorial. To verify this we can run the following command −mysql> select database(); +------------+ | database() | +------------+ | sample | +------------+ 1 row in set (0.00 sec)
Read MoreWhat is the use of escape character () in text file while importing the data from text file to MySQL table?
Use of escape character (\) would become very essential when we want to insert a comma or any other character between the values of a filed. It can be understood with the help of an example. Suppose we want to import the data from a text file named A.txt, having the following data, into a MySQL table −id, Name, Country, Salary 105, Chum, Marsh, USA, 11000 106, Danny, Harrison, AUS, 12000Here, we can see that the filed name has two values first name, last name separated by a comma. Now, the ...
Read MoreHow can we use MySQL INSTR() function with WHERE clause?
When we use INSTR() function with MySQL WHERE clause, we need to provide column name of the table as the first argument and the substring as second argument along with a comparison operator. Following is an example using ‘Student’ table to demonstrate it −ExampleSuppose we have the following values in ‘Student’ table −mysql> Select * from Student; +------+---------+---------+-----------+ | Id | Name | Address | Subject | +------+---------+---------+-----------+ | 1 | Gaurav | Delhi | Computers | | 2 | Aarav | Mumbai | History | | 15 | Harshit | ...
Read MoreHow can we import the text file, having data on the same line with a separator, into MySQL table?
Actually, we can write the data on the same line in the text file by using a separator. In this case, while importing this text file into MySQL table then we must have to use ‘LINES TERMINATED BY’ option. It can be understood with the help of the following example −Suppose we are using ‘|’ as the LINE TERMINATOR symbol in a text file as follows −id, Name, Country, Salary|105, Chum*, Marsh, USA, 11000|106, Danny*, Harrison, AUS, 12000Now while importing this text file into MySQL table then we need to mention ‘LINE TERMINATED BY’ option also in the query as ...
Read MoreHow can we import only specific columns from the text file, into MySQL table?
Suppose if we have the values for some specific columns in the text file and MySQL table, in which we want to import the data, is having an extra column(s) then by mentioning the names of the columns in the query we can upload the values of those specific columns only. It can be understood with the help of the following example −ExampleSuppose we are having the values of columns ‘id’, ‘Name’ and ‘Salary’ only in the text file as follows −105, Chum, 11000 106, Danny, 12000Now while importing this text file into MySQL table then we need to mention ...
Read MoreWhat is the difference between MySQL INSTR() and FIND_IN_SET() functions?
As we know, both the functions are used to search a string from the arguments provided in them but there are some significant differences between them as followsFIND_IN_SET() function uses the string list that is itself a string containing the substring separated by commas. Whereas, INSTR() function contains a string from which it will find the position of the first occurrence of the substring if present. In case of integers, FIND_IN_SET() is much more suitable than INSTR() function. It can be understood by the following exampleExamplemysql> Select IF(INSTR('10, 11, 12, 13', 2) > 0, 1, 0) As Result; +--------+ | Result ...
Read MoreHow it is possible in MySQL to find a string of specified pattern within another string?
We can find a string of specified pattern within another string by using LIKE operator along with WILDCARDS.SyntaxLIKE specific_patternSpecific_pattern is the pattern of string we 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 having the pattern of string ‘av’ within their names. It can be done with the help of following MySQL query −mysql> Select * from Student Where Name LIKE '%av%'; +------+--------+---------+-----------+ | Id | Name | Address | Subject | +------+--------+---------+-----------+ ...
Read MoreHow can we import data from .txt file into MySQL table?
It can be done with the help of LOAD DATA INFILE statement. To illustrate the concept we are having the following data, separated by tab, in ‘A.txt’ whose path is d:/A.txt −100 John USA 10000 101 Paul UK 12000 102 Henry NZ 11000 103 Rick USA 17000 104 Corey USA 15000We want to load the data of A.txt into the following table named employee_tbl −mysql> Create table employee_tbl(Id Int, Name varchar(20), Country Varchar(20), Salary Int); Query OK, 0 rows affected (0.91 sec)Now, the transfer of data from a file to a database table can be done with the help ...
Read MoreWhat happens if the value of number ‘N’ in CONV() function is not as per accordance with its base?
MySQL returns 0 as output if the number given in CONV() function is not as per accordance with its base. Suppose, if we want to convert decimal number 9 into the number in binary number system then in this case the value of from_base must be 10 but if we provide 8 as the value of from_base then MySQL returns 0 as output.Examplemysql> Select CONV(9,8,2); +-------------+ | CONV(9,8,2) | +-------------+ | 0 | +-------------+ 1 row in set (0.00 sec)As we know that the values of octal number system must be between 0 to 7, hence the number system for number 9 must be decimal i.e. 10.
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