Ring/Lessons/MySQL Functions

MySQL Functions

In this chapter we are going to learn about the MySQL functions provided by the Ring programming language. Before using the functions load the mysqllib.ring library:

	load "mysqllib.ring"

MySQL_Info()
MySQL_Init()
MySQL_Error()
MySQL_Connect()
MySQL_Close()
MySQL_Query()
MySQL_Insert_ID()
MySQL_Result()
MySQL_Next_Result()
MySQL_Columns()
MySQL_Result2()
MySQL_Escape_String()
MySQL_AutoCommit()
MySQL_Commit()
MySQL_Rollback()

MySQL_Info() Function

We can get the MySQL Client version using the MySQL_Info() function.

Syntax:

	MySQL_Info() ---> string contains the MySQL Client version

Example:

	see "MySQL Client Version : " + mysql_info()

Output:

	MySQL Client Version : 6.1.5

MySQL_Init() Function

We can start using MySQL Client through the MySQL_Init() function.

Syntax:

	MySQL_Init() ---> MySQL Handle

MySQL_Error() Function

We can get the error message from the MySQL Client using the MySQL_Error() function.

Syntax:

	MySQL_Error(MySQL Handle) ---> Error message as string

MySQL_Connect() Function

We can connect to the MySQL database server using the MySQL_Connect() function.

Syntax:

	MySQL_Connect(MySQL Handle, cServer, cUserName, cPassword) ---> lStatus

MySQL_Close() Function

We can close the connection to the MySQL database using the MySQL_Close() function

Syntax:

	MySQL_Close(MySQL Handle)

MySQL_Query() Function

We can execute SQL queries using the MySQL_Query() function

Syntax:

	
	MySQL_Query(MySQL Handle, cSQLQuery)

Create Database

The next example connect to MySQL Server then create new database.

	See "MySQL Test - Create Database" + nl
	con = mysql_init()

	See "Connect" + nl
	if mysql_connect(con,"localhost","root","root") = 0
		see "Cann't connect" + nl
		see "Error : " + mysql_error(con) + nl
		mysql_close(con)
		bye
	ok

	See "Create Database..." + nl
	mysql_query(con,"CREATE DATABASE mahdb")

	See "Close Connection" + nl
	mysql_close(con)

Output:

	MySQL Test - Create Database
	Connect
	Create Database...
	Close Connection

Create Table and Insert Data

The next example create new table and insert records

	func main
		see "Create Table and Insert Records" + nl
		con = mysql_init()

		see "Connect" + nl
		if mysql_connect(con, "localhost", "root", "root","mahdb") = 0 
			system_error(con) 
		ok

		see "Drop table" + nl
		if mysql_query(con, "DROP TABLE IF EXISTS Employee")  system_error(con) ok
  
		see "Create table" + nl
		if mysql_query(con, "CREATE TABLE Employee(Id INT, Name TEXT, Salary INT)") 
		   system_error(con) ok
 
 		see "Insert data" + nl 
		if mysql_query(con, "INSERT INTO Employee VALUES(1,'Mahmoud',15000)") 
		   system_error(con) ok
  
		if mysql_query(con, "INSERT INTO Employee VALUES(2,'Samir',16000)") 
		   system_error(con) ok

		if mysql_query(con, "INSERT INTO Employee VALUES(3,'Fayed',17000)")  
		   system_error(con) ok

		see "Close connection" + nl
		mysql_close(con) 

	func system_error con
		see mysql_error(con)  mysql_close(con)  bye

Output:

	Create Table and Insert Records
	Connect
	Drop table
	Create table
	Insert data
	Close connection

MySQL_Insert_ID() Function

We can get the inserted row id using the MySQL_Insert_ID() function

Syntax:

	MySQL_Insert_ID() ---> Inserted row id as number

Example:

	con = mysql_init()
	see "connect to database" + nl
	mysql_connect(con,"localhost","root","root","mahdb")
	see "drop table" + nl
	mysql_query(con, "DROP TABLE IF EXISTS Customers")
	see "create table" + nl
	mysql_query(con, "CREATE TABLE Customers(Id INT PRIMARY KEY AUTO_INCREMENT, Name TEXT)")
	see "insert record" + nl
	mysql_query(con, "INSERT INTO Customers(Name) VALUES('Mahmoud')")
	see "insert record" + nl
	mysql_query(con, "INSERT INTO Customers(Name) VALUES('Samir')")
	see "insert record" + nl
	mysql_query(con, "INSERT INTO Customers(Name) VALUES('Fayed')")
	see "insert record" + nl
	mysql_query(con, "INSERT INTO Customers(Name) VALUES('Test 2015')")

see "inserted row id : " + mysql_insert_id(con) + nl see "close database" + nl mysql_close(con)

Output:

	connect to database
	drop table
	create table
	insert record
	insert record
	insert record
	insert record
	inserted row id : 4
	close database

MySQL_Result() Function

We can get the query result (data without column names) using the MySQL_Result() function.

Syntax:

	MySQL_Result(MySQL Handle) ---> List contains the query result

MySQL_Next_Result() Function

We can move to the next query result using the MySQL_Next_Result() function. We use this function when we have multiple SQL statements in the same query.

Syntax:

	MySQL_Next_Result(MySQL Handle)

Print Query Result

The next example execute a query on the database then print the result.

	con = mysql_init()
	see "Connect to database" + nl
	mysql_connect(con, "localhost", "root", "root","mahdb")
	see "Execute Query" + nl
	mysql_query(con, "SELECT Name FROM Employee WHERE Id=1;"+
			 "SELECT Name FROM Employee WHERE Id=3")
	see "Print Result" + nl 
	see mysql_result(con)
	mysql_next_result(con)
	see mysql_result(con)
	see "close database" + nl
	mysql_close(con)

Output:

	Connect to database
	Execute Query
	Print Result
	Mahmoud
	Fayed
	close database

MySQL_Columns() Function

We can get a list of columns names using the MySQL_Columns() function.

Syntax:

	MySQL_Columns(MySQL Handle) ---> List contains columns information

Example:

	con = mysql_init()
	see "Connect to database" + nl
	mysql_connect(con, "localhost", "root", "root","mahdb")
	see "Execute Query" + nl
	mysql_query(con, "SELECT * FROM Employee")
	see "Result" + nl 
	see mysql_columns(con)
	see "Close database" + nl
	mysql_close(con)

Output:

	Connect to database
	Execute Query
	Result
	Id
	11
	3
	32768
	Name
	65535
	252
	16
	Salary
	11
	3
	32768
	Close database

MySQL_Result2() Function

Instead of using MySQL_Result() to get the result data without columns names, we can use the MySQL_Result2() to get all of the column names then the query result in one list.

Syntax:

	MySQL_Result2(MySQL Handle) ---> List (query result starts with columns names)

Example:

	con = mysql_init()
	see "Connect to database" + nl
	mysql_connect(con, "localhost", "root", "root","mahdb")
	see "Execute Query" + nl
	mysql_query(con, "SELECT * FROM Employee")
	see "Print Result" + nl 
	see mysql_result2(con)
	see "Close database" + nl
	mysql_close(con)

Output:

	Connect to database
	Execute Query
	Print Result
	Id
	Name
	Salary
	1
	Mahmoud
	15000
	2
	Samir
	16000
	3
	Fayed
	17000
	Close database

MySQL_Escape_String() Function

We can store binary data and special characters in the database after processing using MySQL_Escape_String() function

Syntax:

	MySQL_Escape_String(MySQL Handle, cString) ---> String after processing

Save Image inside the database

Example:

	See "Read file" + nl
	cFile = read("tests\mahmoud.jpg")
	con = mysql_init()
	See "Connect to database..." + nl
	mysql_connect(con, "localhost", "root", "root","mahdb")
	See "Escape string..." + nl
	cFile = mysql_escape_string(con,cFile)
	stmt = "INSERT INTO photo(id, data) VALUES(1, '" + cFile + "')"
	See "Insert data..." + nl
	mysql_query(con,stmt)
	See "Close database..." + nl
	mysql_close(con)

Output:

	Read file
	Connect to database...
	Escape string...
	Insert data...
	Close database...

Restore Image From The Database

Example:

	con = mysql_init()
	See "Connect to database..." + nl
	mysql_connect(con, "localhost", "root", "root","mahdb")
	See "Read data from database..." + nl
	mysql_query(con,"SELECT data FROM photo WHERE id=1")
	See "Write new file" + nl
	result = mysql_result(con)
	write("tests\mahmoud2.jpg",result[1][1])
	See "Close database..." + nl
	mysql_close(con)

Output:

	Connect to database...
	Read data from database...
	Write new file
	Close database...

MySQL_AutoCommit() Function

We can enable or disable the auto commit feature using the MySQL_AutoCommit() function.

Syntax:

	MySQL_AutoCommit(MySQL Handle, lStatus)  # lstatus can be True/False

MySQL_Commit() Function

We can commit updates to the database using the MySQL_Commit() function.

Syntax:

	MySQL_Commit(MySQL Handle)

MySQL_Rollback() Function

We can rollback updates to the database using the MySQL_Rollback() function.

Syntax:

	MySQL_Rollback(MySQL Handle)

Transaction Example

The next example presents the usage of MySQL_Autocommit(), MySQL_Commit() & MySQL_RollBack() functions.

Example:

	func main
	
		con = mysql_init()

		see "Connect" + nl
		if mysql_connect(con, "localhost", "root", "root","mahdb") = 0 
			system_error(con) ok

		see "Drop table" + nl
		if mysql_query(con, "DROP TABLE IF EXISTS Employee2") 
			system_error(con) ok
  
		see "Create table" + nl
		if mysql_query(con, "CREATE TABLE Employee2(Id INT, Name TEXT, Salary INT)")
			system_error(con) ok
 
 		see "Insert data" + nl 
		if mysql_query(con, "INSERT INTO Employee2 VALUES(1,'Mahmoud',15000)") 
			system_error(con) ok
  
		if mysql_query(con, "INSERT INTO Employee2 VALUES(2,'Samir',16000)")
			system_error(con) ok

		if mysql_query(con, "INSERT INTO Employee2 VALUES(3,'Fayed',17000)") 
			system_error(con) ok

		mysql_autocommit(con,False)
		mysql_query(con, "INSERT INTO Employee2 VALUES(4,'Ahmed',5000)")
		mysql_query(con, "INSERT INTO Employee2 VALUES(5,'Ibrahim',50000)")
		mysql_query(con, "INSERT INTO Employee2 VALUES(6,'Mohammed',50000)")
		See "Save transaction (y/n) " give nChoice
		if upper(nChoice) = "Y"
			mysql_commit(con)
		else
			mysql_rollback(con)
		ok

		see "Close connection" + nl
		mysql_close(con) 

	func system_error con

		see mysql_error(con)
		mysql_close(con)
		bye

Output:

	Connect
	Drop table
	Create table
	Insert data
	Save transaction (y/n) y
	Close connection

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