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- Python MySQL - Limit
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- Python MySQL - Cursor Object
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Python MySQL - Where Clause
If you want to fetch, delete or, update particular rows of a table in MySQL, you need to use the where clause to specify condition to filter the rows of the table for the operation.
For example, if you have a SELECT statement with where clause, only the rows which satisfies the specified condition will be retrieved.
Syntax
Following is the syntax of the WHERE clause −
SELECT column1, column2, columnN FROM table_name WHERE [condition]
Example
Assume we have created a table in MySQL with name EMPLOYEES as −
mysql> CREATE TABLE EMPLOYEE( FIRST_NAME CHAR(20) NOT NULL, LAST_NAME CHAR(20), AGE INT, SEX CHAR(1), INCOME FLOAT ); Query OK, 0 rows affected (0.36 sec)
And if we have inserted 4 records in to it using INSERT statements as −
mysql> INSERT INTO EMPLOYEE VALUES ('Krishna', 'Sharma', 19, 'M', 2000), ('Raj', 'Kandukuri', 20, 'M', 7000), ('Ramya', 'Ramapriya', 25, 'F', 5000), ('Mac', 'Mohan', 26, 'M', 2000);
Following MySQL statement retrieves the records of the employees whose income is greater than 4000.
mysql> SELECT * FROM EMPLOYEE WHERE INCOME > 4000; +------------+-----------+------+------+--------+ | FIRST_NAME | LAST_NAME | AGE | SEX | INCOME | +------------+-----------+------+------+--------+ | Raj | Kandukuri | 20 | M | 7000 | | Ramya | Ramapriya | 25 | F | 5000 | +------------+-----------+------+------+--------+ 2 rows in set (0.00 sec)
WHERE clause using python
To fetch specific records from a table using the python program −
import mysql.connector package.
Create a connection object using the mysql.connector.connect() method, by passing the user name, password, host (optional default: localhost) and, database (optional) as parameters to it.
Create a cursor object by invoking the cursor() method on the connection object created above.
Then, execute the SELECT statement with WHERE clause, by passing it as a parameter to the execute() method.
Example
Following example creates a table named Employee and populates it. Then using the where clause it retrieves the records with age value less than 23.
import mysql.connector #establishing the connection conn = mysql.connector.connect( user='root', password='password', host='127.0.0.1', database='mydb') #Creating a cursor object using the cursor() method cursor = conn.cursor() #Doping EMPLOYEE table if already exists. cursor.execute("DROP TABLE IF EXISTS EMPLOYEE") sql = '''CREATE TABLE EMPLOYEE( FIRST_NAME CHAR(20) NOT NULL, LAST_NAME CHAR(20), AGE INT, SEX CHAR(1), INCOME FLOAT )''' cursor.execute(sql) #Populating the table insert_stmt = "INSERT INTO EMPLOYEE (FIRST_NAME, LAST_NAME, AGE, SEX, INCOME) VALUES (%s, %s, %s, %s, %s)" data = [('Krishna', 'Sharma', 19, 'M', 2000), ('Raj', 'Kandukuri', 20, 'M', 7000), ('Ramya', 'Ramapriya', 25, 'F', 5000),('Mac', 'Mohan', 26, 'M', 2000)] cursor.executemany(insert_stmt, data) conn.commit() #Retrieving specific records using the where clause cursor.execute("SELECT * from EMPLOYEE WHERE AGE <23") print(cursor.fetchall()) #Closing the connection conn.close()
Output
[('Krishna', 'Sharma', 19, 'M', 2000.0), ('Raj', 'Kandukuri', 20, 'M', 7000.0)]