Data with : An Tool for

One of the most tools for is the . are used to on a or set of in a table. This that data is not into the table, which can cause data . In this , we will the of and how they help data .

A is a that any from being into a in a table. This can be used to on a , or on a of . For , if we have a table that , we may want to that each has a email . This can be by a on the email .

When a is on a , the will check for when data is or in the table. If a value is found, the will throw an error and the data from being into the table. This helps to that the data in the table is and free of .

are they help data . Data is the and of data in a . data , the data in a may be and . For , if we have a table that , we may want to that each order has a order ID. If two have the same order ID, it would be to know which order is which. This could lead to and in .

By on a or set of , we can that the data in the table is and free of . This makes it to work with the data and that it can be upon for -.

In to data , also have other . One is . When a is on a , the can use an index to look up in the . This can speed up and the of the .

of is that they can be used to . is the of in a . For , if we have a table that , we may want to link each order to a in table. By a on the ID in the table, we can that each order is to a valid . This helps to data and in the .

In , are an tool for data in a . By on a or set of , we can that the data in the table is and free of . This makes it to work with the data and that it can be upon for -. also have other , such as and the to . For these , it is to use when and a .