Let our view choose the ratio of views to the number of responses for the topics in the forum:ĬREATE VIEW v AS SELECT subject, num_views/num_replies AS param FROM topics WHERE num_replies>0 įor this view, each row corresponds to a single row from the topics table, i.e. Using the MERGE algorithm requires a 1 to 1 match between the rows of the table and the view based on it. This is the default value if this construct is missing. UNDEFINED means that MySQL chooses which algorithm to use when accessing a view. To create a view, the CREATE VIEW statement is used with the following syntax: Only the views that satisfy a number of requirements allow the UPDATE, DELETE and INSERT type queries.The tables and submissions that are present in the definition of a submission must exist.You cannot use parameters of prepared expressions (PREPARE) in determining the representation.You cannot use system and user variables in the view definition you cannot use local variables or procedure parameters within stored procedures in the view definition. A subquery in the FROM part of the definition of a view cannot be used.You cannot make a submission based on temporary tables you cannot make a temporary submission.You cannot hang the trigger on the view.The article contains restrictions for MySQL 5.1 version (their number may decrease later).The article contains restrictions for MySQL 5.1 version (their number may decrease later). Easy to use by automatically performing actions such as accessing a certain part of rows and/or columns, retrieving data from multiple tables and converting them using different functions.It’s very convenient when you can’t change the program code or when several applications with different data structure requirements address the same database. You can change the data structure without affecting the program code, you just need to create views similar to the tables that were previously accessed by applications.
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