JOIN combines several tables to retrieve their data with a single query. The second option is to use the JOIN clause. You specify the column names after the FROM clause and separate them by commas. The first one is to define which tables the command should refer to. The SELECT query in MySQL offers two options. In your work, you often need to retrieve the data from several tables simultaneously. In most cases, databases contain multiple tables with different data. The results will be present in ascending order. This command returns the data on the book titles, quantities of items, and names of the authors for the books with a price less than $15. If we want to select specific fields from the table, we must specify them in the SELECT statements: SELECT book_title, quantity, author_name, book_price We use the “asterisk” option to get all fields from the book_prices table with the quantity greater or equal to 15. Have a look at the following example: SELECT * The simplest case of using the MySQL SELECT command is retrieving all data in a table according to a particular criterion. The solution is to always specify the target column names to retrieve the data from. One more problem, if the table gets changed, for instance, someone adds new columns without notifying you, SELECT * will bring you the data you did not expect, spoiling your plans and results. This may overload the network traffic and produce unnecessary I/O. MySQL SELECT * returns all data even from those columns that you don’t use and don’t need for this query. SELECT * – “asterisk” – is a replacement for the ALL clause and quite a popular method.
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