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MySQLi Articles
Page 309 of 341
Count how many rows have the same value in MySQL?
To count how many rows have the same value using the function COUNT(*) and GROUP BY. The syntax is as follows −SELECT yourColumName1, count(*) as anyVariableName from yourTableName GROUP BY yourColumName1;To understand the above syntax, let us first create a table. The query to create a table is as follows −mysql> create table RowWithSameValue −> ( −> StudentId int, −> StudentName varchar(100), −> StudentMarks int −> ); Query OK, 0 rows affected (0.55 sec)Insert some records with same value. Here, we have added same marks for more than one student for our example. The query ...
Read MoreSearch for a string within text column in MySQL?
You can search for a string within text column in MySQL with the help of LIKE clause. The syntax is as follows −select *from yourTableName where yourColumnName like '%anyStringValue%';To use the above syntax, let us first create a table −mysql> create table SearchTextDemo −> ( −> BookName TEXT −> ); Query OK, 0 rows affected (0.55 sec)Insert some strings in the table. The query is as follows −mysql> insert into SearchTextDemo values('Let us C'); Query OK, 1 row affected (0.28 sec) mysql> insert into SearchTextDemo values('C in Depth'); Query OK, 1 row affected (0.14 sec) ...
Read MoreHow to change the column position of MySQL table without losing column data?
You can change the column position of MySQL table without losing data with the help of ALTER TABLE command. The syntax is as follows −ALTER TABLE yourTableName MODIFY yourColumnName1 data type AFTER yourColumnName2;To understand the above concept, let us create a table. The query to create a table with some columns is as follows −mysql> create table changeColumnPositionDemo −> ( −> StudentId int, −> StudentAddress varchar(200), −> StudentAge int, −> StudentName varchar(200) −> ); Query OK, 0 rows affected (0.72 sec)Let us insert some data in the table. The query to insert records is as follows -.mysql> insert into changeColumnPositionDemo ...
Read MoreHow to get primary key of a table in MySQL?
To get the primary key of a table, you can use the show command. The syntax is as follows −SHOW INDEX FROM yourDatebaseName.yourTableName WHERE Key_name = 'PRIMARY';Suppose, we have a table with two primary keys; one of them is “Id” and second is “RollNum". The query for a table is as follows −mysql> create table TwoOrMorePrimary −> ( −> Id int, −> Name varchar(200), −> RollNum int −> , −> Primary key(Id, Age) −> ); Query OK, 0 rows affected (0.85 sec)Apply the above syntax to get primary key of a table. ...
Read MoreDo a select in MySQL based only on month and year?
To select MySQL based on month and year, use in-built function YEAR() and MONTH(). The syntax is as follows −select *from yourTableName where YEAR(yourColumnName) = YearValue AND MONTH(yourColumnName) = monthValue;To understand the above syntax, let us create a table. The query to create a table is as follows −mysql> create table selectDataOnYearandMonthDemo −> ( −> BookId int, −> BookName varchar(100), −> BookDueDate datetime −> ); Query OK, 0 rows affected (0.57 sec)Now you can insert some records in the table. The query is as ...
Read MoreHow to front pad zip code with “0” in MySQL?
To front pad zip code with 0, use LPAD() function in MySQL. The syntax is as follows −SELECT LPAD(yourColumnName, columnWidth+1, '0') as anyVariableName from yourTableName;To understand the above concept of LPAD() to add front pad zip code with 0, let us create a table. One of the columns of the table is Zip Code. The following is the query to create a table.mysql> create table ZipCodePadWithZeroDemo −> ( −> Name varchar(200), −> YourZipCode int(6) −> ); Query OK, 0 rows affected (0.44 sec)Insert some records in the table. The query to insert records is as follows ...
Read MoreGroup month and year in MySQL?
You can group month and year with the help of function DATE_FORMAT() in MySQL. The GROUP BY clause is also used.The syntax is as follows −SELECT DATE_FORMAT(yourColumnName, '%m-%Y') from yourTableName GROUP BY MONTH(yourColumnName), YEAR(yourColumnName)DESC;To understand the above concept, let us create a table. The following is the query to create a table −mysql> create table GroupMonthAndYearDemo −> ( −> DueDate datetime −> ); Query OK, 0 rows affected (1.49 sec)Insert records in the table using the following query −mysql> insert into GroupMonthAndYearDemo values(now()); Query OK, 1 row affected (0.11 sec) ...
Read MoreHow can I describe all tables in the database through a single statement in MySQL?
You can use INFORMATION_SCHEMA.COLUMNS to describe all tables in database through a single statement. The syntax is as follows.SELECT *FROM INFORMATION_SCHEMA.COLUMNS WHERE TABLE_SCHEMA=’yourDatabaseName’\GHere I am using my database sample with two tables.The table names are as follows −mytableyourtableImplement the above syntax for your database. The query is as follows −mysql> select * FROM information_schema.columns WHERE table_schema = 'sample'\GThe following is the output describing the two tables in our database.*************************** 1. row *************************** TABLE_CATALOG: def TABLE_SCHEMA: sample TABLE_NAME: mytable COLUMN_NAME: id ORDINAL_POSITION: 1 COLUMN_DEFAULT: NULL IS_NULLABLE: YES DATA_TYPE: int CHARACTER_MAXIMUM_LENGTH: NULL CHARACTER_OCTET_LENGTH: NULL NUMERIC_PRECISION: 10 NUMERIC_SCALE: 0 DATETIME_PRECISION: NULL CHARACTER_SET_NAME: NULL ...
Read MoreHow to count distinct values in MySQL?
To count distinct values, you can use distinct in aggregate function count().The syntax is as follows −select count(distinct yourColumnName) as anyVariableName from yourTableName;To understand the above concept, let us create a table. The following is the query to create a table −mysql> create table DistinctDemo −> ( −> Name varchar(200) −> ); Query OK, 0 rows affected (0.58 sec)For our example, let us insert duplicate records in the table. The query to insert records is as follows −mysql> insert into DistinctDemo values('John'); Query OK, 1 row affected (0.15 sec) mysql> ...
Read MorePerform MySQL delete under safe mode?
To delete under safe mode, you can use the below query −SET SQL_SAFE_UPDATES = 0;To understand the above query, let us create a table. The following is the query to create a table −mysql> create table SafeDeleteDemo −> ( −> Price int −> ); Query OK, 0 rows affected (0.50 sec)Insert some records in the table with the help of insert command. The query is as follows −mysql> insert into SafeDeleteDemo values(100); Query OK, 1 row affected (0.11 sec) mysql> insert into SafeDeleteDemo values(200); Query OK, 1 row affected (0.19 sec) mysql> insert into SafeDeleteDemo ...
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