You use DML statements to manipulate and process database values. You can insert new rows into a table, update one or more values in stored rows, or delete a row.
The following table list some basic DML statements. The list is not exhaustive.
Statement | Action |
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CHECKPOINT | Checkpoints a journal. That is, defines a recovery point in the journal that can later be used to restore the table contents to its state at that time. Useful if table contents become incorrect due to hardware failure or operational error. |
DELETE | Removes one ore more rows from a table. |
ECHO | Echoes a string or command to a client. |
INSERT | Inserts one ore more new rows into a table. For information about a special case of INSERT, see Atomic Upsert later in this table. |
MERGE | Combines UPDATE and INSERT in a single SQL statement. Supports primary index operations only, similar to Atomic Upsert but with fewer constraints. |
|
Enable you to manage transactions. |
SELECT | Returns specific row data as a result table. |
UPDATE | Modifies data in one or more rows of a table. |
Atomic Upsert This form of the UPDATE statement is a database extension of the ANSI/ISO SQL standard, designed to enhance the performance of the TPump utility. For more information about how TPump operates, see Teradata Parallel Data Pump. Atomic Upsert allows Teradata TPump and all other CLIv2-, ODBC-, and JDBC-based applications to perform single-row upsert operations using an optimally efficient single-pass strategy. This single-pass upsert is called atomic because its component UPDATE and INSERT SQL statements are performed as a single SQL statement. |