What is a Table Type in ABAP?

A table type in ABAP is a data type definition for internal tables. Internal tables are a core component in ABAP for handling collections of records in memory, akin to arrays in other programming languages but more powerful due to their ability to handle complex data structures. Table types allow developers to define these structures once and reuse them across various programs, ensuring consistency and reducing redundancy.

Key Components of Table Types

1. Line Type: This defines the structure of each row in the table. It can be a predefined data element, a structure, or another table type.
2. Access Mode: Specifies how the table will be accessed and stored. The primary types are:

         Standard Table: The default table type with no specific key.

         Sorted Table: Maintains data in a sorted order based on key fields.

         Hashed Table: Allows fast access to rows via a unique key.

3. Key Fields: essential for sorted and hashed tables, these fields define the unique identifiers for table rows.

Steps to Create a Table Type

Creating a table type in ABAP involves using the ABAP Dictionary (transaction SE11). Follow these steps to create a table type:

Step 1: Open ABAP Dictionary (SE11)

1. Enter the transaction code SE11 in the command field and press Enter.

Step 2: Select Data Type

1. Choose the “Data Type” radio button.
2. Enter a name for the table type (e.g., ZMY_TABLE_TYPE). Remember, custom objects should start with Z or Y.

Step 3: Create the Table Type

1. Click on the “Create” button.
2. In the pop-up window, select “Table Type” and confirm with the green checkmark.

Step 4: Define the Line Type

1. In the “Line Type” field, specify the structure or data element that will define the row structure. You can use an existing structure or create a new one if needed.

Step 5: Set Access Mode

1. Define the “Access Mode” according to your needs:

   Standard Table: Default option, no specific order or key.

   Sorted Table:  Data is sorted based on specified key fields.

   Hashed Table: Optimized for quick key-based access.

Step 6: Define Key Fields

1. If using a sorted or hashed table, specify the key fields in the “Key Fields” section.

Step 7: Save and Activate

1. Save the table type by clicking on the save button (Ctrl+S).
2. Assign it to a package or a temporary package ($TMP) if it’s a local object.
3. Finally, activate the table type by clicking on the activate button (Ctrl+F3).