data mart schema

: Strict_trans_tables and Strict_all_tables. Strict_trans_tables enforces strict patterns on the tables that support transactions, and Strict_all_talbes performs strict mode on all tables.SET [global| SESSION] sql_mode=' strict_trans_tables '; MySQLSET [global| SESSION] sql_mode=' strict_all_tables ';3.ANSI mode:Change the syntax and behavior of the operation to make it more appropriate for standard SQL.Third, the data dictionary:A

4.5 Speed The alter TABLE operationPrinciple:The performance of the ALTER TABLE operation for MySQL is a big problem for large tables.MySQL performs most of the modification of table structure operations by creating an empty table with the new structure, identifying all the data from the old table to insert a new table, and then deleting the old table. This can take a long time, especially if there is not enough memory and the table is large, and ther