Lesson 16 | Slide:1 of 16 Acc

Table Design - II

Lesson

Lesson 16 | Slide:2 of 16 Acc

Content

In this lesson you will :-

Discuss the issues related to table design

modifications

Discuss what is field deletion and insertions

Explain the impact of changing the Primary key and

data type

Discussion what is copy and deletion of tables

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Table Design Modifications

Modifying design of a table comes with its own set of

restrictions and therefore it is of great importance to design the

table structure in detail and to stabilize the table structure to

minimize the chances of design modifications.

This lesson discusses table modifications limited to following

aspects only:

Changing table name

Changing the primary key

Changing field data type

Deletion or insertion of fields

Changing order of fields

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Changing Table Name

Right-click the table on the Navigation Pane and select the Rename option.

Or as a shortcut, you can Press F2 on the selected table to rename it.

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Changing Primary Key

Before changing the primary key of a table having

records, ensure that:

The field is not having duplicate values

The field is not empty

You can change easily change primary key of an

empty table.

Primary Key of a table should be rarely changed

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Changing Field Data Type

Consider following aspects while modifying field’s data type or field size having existing values:

The new data type can support old values. Changing Number to Text is possible since all Numbers values

are accepted by Text.

Changing Text to Number may not be possible since all Text values are not supported by Number.

Old values can fit in the new field size. if you change a field with data type Text and field size 10 to field

size of 5, the existing field values will be lost.

Access displays warning messages when there is a conflict during data type change or field size change

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Adding a New Field

You can add new field to an existing table structure by

defining an additional field after the last existing field.

You can also add or insert a new field in between

existing fields by right-clicking on the table structure

and then selecting the insert row option.

You will need to enter values for the new field for each

existing record.

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Deleting a Field

You can easily delete a field by selecting the field

followed by using the delete button.

You can also delete a field by right-clicking on the field

and then selecting the Delete Rows option.

Remember that the field values for each record are

permanently lost once a field is deleted.

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Adding, Deleting a Field

Click on Insert

Rows to add field

Click on Delete Rows

to remove field

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Changing Order of Fields

To change the order of a field, select the field and then drag and drop before or after the desired field.

Note that changing the order of fields does not lead to any loss of data.

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Deleting Table

You can delete a table by selecting the table on the

Navigation pane and ten pressing the delete key.

A table can also be deleted by right-clicking on the

table and then selecting the delete option.

Deleting a table permanently deletes the table

structure and its records.

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Copying Table

You can copy a table in the following three different

manners:

Copying Structure only: You only copy the structure of

the table but not its records.

Copying Structure and Data: You copy both the table

structure as well as the table records.

Append Data to Existing table: You add the records of a

table to an existing table. For this option to work, the table

structure of the destination table must be identical as that

of the source table.

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Copying Table

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Table Modification Tips

Carefully design the table structure. Stabilize the

structure before inserting records

Avoid changing primary key

During changing field’s data type ensure that existing

values can be supported

Always keep a copy of original table and its records

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Wrap-up

Access does not allow a field to be assigned as a primary key if it contains duplicate values.

During table design modifications, you can either change the data type of a field or change its field size.

Changing a field size from a larger size to a smaller size may lead to loss of data in the existing field values.

Deleting a field leads to a permanent loss of field values.

Access allows you to change the order of the fields in a table structure.

You can copy the table structure, or table structure and data or only data to an existing table.

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End of Lesson 16