Inserting updating and deleting database records

You can verify that the two students were deleted, by selecting all the records from the Students table as following:. And then you tried to insert or update a value on that column with a value that conflicts with this constraint.

You should understand what is a database transaction. The term database transaction is a list of SQLite operations insert or update or delete. The database transaction must be executed as one unit, either all of the operations executed successfully or not at all. All the operations will be cancelled if one of them failed to execute. The transaction for transferring money from one bank account to another will involve a couple of activities. This transaction operation includes the withdrawal of money from the first account, and depositing it into another account.

This transaction must fully completed or fully cancelled and not to fail halfway. With lots of savvy systems in place, often that data is added seamlessly to its intended databases. First, we need to identify the table we're wanting to insert rows into.

Next, we specify the columns we want to fill. Finally, we stipulate the values we need to add. One of the doctors at Mickey Mouse Children's Hospital has a newborn patient who has not yet been named. The doctor needs to enter the baby into the database immediately in order to access a drug trial for the sick child, but the system won't allow the littlun's file to be submitted without a name. The doctor wants the patient to be added using her patient number, with her name left blank until a later date.

As the administrator, you'll need to enter the patient manually into the database. As you can see, we're not only giving the name of the table we need to insert into but also the names of the columns and values we want to add.

We don't specify the PatientID in the column list because as an identity column, this is automatically populated. Because we want to keep the patient's name blank for now, we write NULL for the name columns. To insert more than one row of data with just one statement, use parentheses and commas to specify the distinct new rows. Use a transaction to test out your insert without committing and permanently altering your table.

Below is how we'd add a transaction to the above example:. Need to insert one or multiple rows of data from one table into another table? Let's say several of our young patients are taking part in a new drug trial, and you're setting up a new table to record their participation. The basic structure of this statement is:.

Among other things, CTE can be used to create a temporary result set which can be reused during the query. Here's how the same command written as a CTE would look:. Use it to change a column value for one or multiple rows. Then we use the SET clause which details the columns we want to update.

Because a new column value can affect more than one row, make sure you're happy with the extent of your update before committing! Here's an example using our case study. To modify the data that is currently in a table, you use the UPDATE statement, which is commonly referred to as an update query.

To update all the records in a table, specify the table name, and then use the SET clause to specify the field or fields to be changed. To delete the data that is currently in a table, you use the DELETE statement, which is commonly referred to as a delete query. This is also known as truncating a table. The DELETE statement does not remove the table structure—only the data that is currently being held by the table structure.

To remove all the records from a table, use the DELETE statement and specify which table or tables from which you want to delete all the records. Have questions or feedback about Office VBA or this documentation?