Search results
Results From The WOW.Com Content Network
It also supports >REPLACE INTO syntax, [6] which first attempts an insert, and if that fails, deletes the row, if exists, and then inserts the new one. There is also an IGNORE clause for the INSERT statement, [ 7 ] which tells the server to ignore "duplicate key" errors and go on (existing rows will not be inserted or updated, but all new rows ...
Sorting or ordering the data based on a list of columns to improve search performance; Joining data from multiple sources (e.g., lookup, merge) and deduplicating the data; Aggregating (for example, rollup – summarizing multiple rows of data – total sales for each store, and for each region, etc.) Generating surrogate-key values
For example, if suggesting that Foo be merged into Bar, create a proposal in a new section at Talk:Bar. Start a new section at the bottom of that talk page and include the proposal itself, the list of the affected pages, and a merge rationale. A good example is the following section:
For this example it is assumed that each book has only one author. A table that conforms to the relational model has a primary key which uniquely identifies a row. In our example, the primary key is a composite key of {Title, Format} (indicated by the underlining):
One method for deduplicating data relies on the use of cryptographic hash functions to identify duplicate segments of data. If two different pieces of information generate the same hash value, this is known as a collision. The probability of a collision depends mainly on the hash length (see birthday attack).
This technique can either supplement or complement timestamps and versioning. It can configure an alternative if, for example, a status column is set up on a table row indicating that the row has changed (e.g., a boolean column that, when set to true, indicates that the row has changed).
Either way, it is possible to define them all in one go (possibly as a list-defined reference) and invoke them several times (possibly with different |page= parameters, or to define the citations individually and combine them through the annotation system of template {}. The following examples illustrate the latter form:
A graph exemplifying merge sort. Two red arrows starting from the same node indicate a split, while two green arrows ending at the same node correspond to an execution of the merge algorithm. The merge algorithm plays a critical role in the merge sort algorithm, a comparison-based sorting algorithm. Conceptually, the merge sort algorithm ...