# Relational Data and KV Transformation: Table Number

| `TableID` | `Row No.` | ...  | Name    | Birthday     | Cell phone | Score |
| :-------- | :-------- | :--- | :------ | :----------- | :--------- | :---- |
| `T24`     | 1         | ...  | `Tom`   | `1982-09-28` | 1390811212 | 78    |
| `T24`     | 2         | ...  | `Jack`  | `1996-04-12` | 1801222187 | 91    |
| `T24`     | 3         | ...  | `Frank` | `1982-09-28` | 1364571212 | 90    |
| `T24`     | 4         | ...  | `Tony`  | `1977-03-12` | 1391113134 | 65    |
| `T24`     | 5         | ...  | `Jim`   | `1992-07-19` | 1579915611 | 51    |
| `T24`     | 6         | ...  | `Sam`   | `1978-09-12` | 1713665011 | 97    |

------------------------------------------------------------
We need to add unique TableID to Key, which is the unique number of the table and the index's unique number IndexID for the case of index. In this way, a row has a database-level global key. 

For tables that don't have a primary key, TiDB will add a hidden column `_tidb_rowid` to all relational tables. If the table has INT type Primary Key, then the value of the primary key will be used as the row key for key-value. Where TableID is unique in the whole cluster, IndexID and RowID is unique in the table, and these IDs are of type INT64.