Required SQL statement (4) data deletion and update, SQL statement

Required SQL statement (4) data deletion and update, SQL statement

1. Delete

1) delete records
Delete from table name where id = 'xx'

2) Delete all data and return to the initialization Id field.
Truncate table name

3) differences between delete and truncate
A. truncate enables seeds to return to the initial value.
B. The truncate clause cannot be used.
C. truncate does not involve triggers
D. truncate performance is much higher than delete Performance

2. Update

1) Basic update
Update table name
Set [column name] = 'value'
Where [column name] = 'value'

2) used with replace
-- Replace 'start' with 'in a name over 19 years old'★'.
Update table name
Set name = replace (name, 'start ','★')
Where age> 19