Duplicate Key Update Select

The statement above sets the value of the c1 to its current value specified by the expression values(c1) plus 1 if there is a duplicate in unique index or primary key. mysql insert on duplicate key update example. let’s take a look at an example of using the insert on duplicate key update to understand how it works.. On duplicate key update statement. in other words, values(col_name) in the on duplicate key update clause refers to the value of col_name that would be inserted, had no duplicate-key conflict occurred. this function is especially useful in multiple-row inserts.. Here is a nice tip for insert into select on duplicate key update. better than jon webb's example mentioned above. the trick is to use user-defined variable to store computed data, so that it is not need to be computed again..

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On duplicate key update syntax” for conditions under which the select columns can be referred to in an on duplicate key update clause. the order in which a select statement with no order by clause returns rows is nondeterministic.. Select statements, these rules apply regarding acceptable forms of select query expressions that you can refer to in an on duplicate key update clause: references to columns from queries on a single table, which may be a derived table.. Insert into t1(a, b, c) select d, e, f from t2 on duplicate key update b = values(b), c = values(c); the disadvantage to this approach is lack of portability, of course. inserting and updating in a single statement is highly non-standard..

duplicate key update select

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