A transaction is a collection of SQL statements.\u00a0 So a task may, for example, consist of a number of update statements.\u00a0 If one of these should fail you may end up with some tables correctly updated but others not correctly updated particularly if one update has data from a previous update.<\/p>\n
To overcome this you define the SQL statements as a transaction<\/strong>. If one SQL statement should fail, you roll back the data to its initial state.\u00a0 Only when all the statements are successful will you commit the transaction.<\/p>\n When you are entering SQL statements into mySQL you may use the begin \/ commit \u00a0\/ rollback transaction commands.<\/p>\n So, say we are working with a person<\/strong> table and do an INSERT<\/strong> statement, we can either commit or rollback the transaction.<\/p>\n The problem with\u00a0phpMyAdmin<\/strong> is that all the lines have to be in one command so it is not easy to demonstrate.<\/p>\n However, we can demonstrate it using the following SQL statements and check the results for each.<\/p>\n Copy the following lines in to the SQL editor in phpMyAdmin<\/strong>:<\/p>\n begin;<\/strong> Examine the person table.\u00a0 We should see that a new record has been created.<\/p>\n Now copy the following lines into the SQL editor in phpMyAdmin<\/strong>:<\/p>\n begin;<\/strong> In this case the transaction has been rolled back and the record has not been created.<\/p>\n","protected":false},"excerpt":{"rendered":" A transaction is a collection of SQL statements.\u00a0 So a task may, for example, consist of a number of update statements.\u00a0 If one of these should fail you may end up with some tables correctly updated but others not correctly…<\/span><\/p>\n
\nINSERT INTO person (firstname, lastname) VALUES (“fred”, “blogs”);
\ncommit;<\/strong><\/p>\n
\nINSERT INTO person (firstname, lastname) VALUES (“fred”, “blogs”);
\nrollback;<\/strong><\/p>\n