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.

mysqlimport can be run with a number of options. Followings are some options for mysqlimport and their effect on import.OptionAction-r or –replaceCause imported rows to overwrite existing rows if they have the same unique key value.-i or –ignoreIgnore rows that have the same unique key value as existing rows.-f or –forceForce mysqlimport to continue inserting data even if errors are encountered.-l or --lock-tablesLock each table before importing (a good option on a busy server).-d or –deleteEmpty the table before inserting.--fields-terminated- by='char'Specify the separator used between values of the same row, default \t (tab).--fields-enclosed- by='char'Specify the delimiter that encloses each field; ... Read More

With the help of mysqlimport we can upload data into multiple MySQL tables. It is illustrated in the example below −ExampleSuppose we want to upload the following data from two data files namely student1_tbl.txt −1     Saurav     11th 2     Sahil      11th 3     Digvijay   11thAnd House.txt1   Furniture 2   Television 3   RefrigeratorFollowings are MySQL tables into which we want to upload the above data −mysql> DESCRIBE Student1_tbl; +--------+-------------+------+-----+---------+-------+ | Field  | Type        | Null | Key | Default | Extra | +--------+-------------+------+-----+---------+-------+ | RollNo | int(11) ... Read More

For uploading the data into MySQL tables by using mysqlimport we need to follow following steps −Step-1 − Creating the tablefirst of all, we need to have a table in which we want to upload the data. We can use CREATE TABLE statement for creating a MySQL table. For example, we created a table named ‘student_tbl’ as follows −mysql> DESCRIBE Student_tbl; +--------+-------------+------+-----+---------+-------+ | Field | Type         | Null | Key | Default | Extra | +--------+-------------+------+-----+---------+-------+ | RollNo | int(11)     | YES  |     | NULL    |       | | ... Read More

Transferring the information between MySQL and data files mean importing data from data files into our database or exporting data from our database into files. MySQL is having two commands that can be used to import or export data between MySQL and data files through the command line −mysqlimport Actually, mysqlimport command reads a spread of data formats, including comma-and tab-delimited, and inserts the information into a database. In other words, we can say that it provides a command-line interface for importing the data i.e. command-line interface to the LOAD DATA INFILE statement. Its syntax would be as follows −SyntaxMysqlimport [options] ... Read More

MySQL throws this error because of the two reasons, either no directory is specified under --secure--file--priv variable or we are giving the wrong path in our query while importing or exporting the data. To tackle this error we must have to check the value of –secure—file—priv variable by following query −mysql> Select @@global.secure_file_priv; +---------------------------+ | @@global.secure_file_priv | +---------------------------+ | C:\mysql\bin\mysql-files\ | +---------------------------+ 1 row in set (0.00 sec)We can see there is path under secure_file_priv variable and all the files would be created under this directory when we export the data.But, if the above command shows NULL as result then ... Read More

If we want to store any other value than \N in CSV file on exporting the data to CSV file from a table which contains NULL value(s) then we need to replace \N values with other value by using IFNULL statement. To illustrate it we are taking the following example −ExampleSuppose if we want to export the values of the table ‘student_info’ having the following data −mysql> Select * from Student_info; +------+---------+------------+------------+ | id   | Name    | Address    | Subject    | +------+---------+------------+------------+ | 101  | YashPal | Amritsar   | History    | | 105  | ... Read More

If we export the data from a table having NULL values then MySQL will store \N in CSV file for the record MySQL table having NULL values. It can be illustrated with the help of the following example −ExampleSuppose if we want to export the values of the table ‘student_info’ having the following data −mysql> Select * from Student_info; +------+---------+------------+------------+ | id   | Name    | Address    | Subject    | +------+---------+------------+------------+ | 101  | YashPal | Amritsar   | History    | | 105  | Gaurav  | Chandigarh | Literature | | 125  | Raman   | ... Read More

For adding the column values we need to use UNION statement. It can be demonstrated with the help of the following example −ExampleIn this example data from student_info will be exporting to CSV file. The CSV file will have the first line as the name of the columns.mysql>(SELECT 'id', 'Name', 'Address', 'Subject')UNION(SELECT id, Name, Address, Subject From student_info INTO OUTFILE 'C:/mysql/bin/mysql-files/student_25.CSV' FIELDS ENCLOSED BY '"' TERMINATED BY ';' ESCAPED BY '"' LINES TERMINATED BY '\r'); Query OK, 7 rows affected (0.04 sec)After executing the above query MySQL creates Student_25.CSV file which have the following values −id;    "Name";     ... Read More