"MySQL must know" study notes (iii)

Concat is used to splice strings, such as Select Concat (RTrim (Vend_name), ' (', RTrim (vend_country), ') ') from vendors;

Where RTrim is used to remove the right side of the space, concat in multiple strings, connected.

In addition, it is usually accompanied by the use of a field alias to be called at the client.

You can also calculate with arithmetic in the selected field, such as select Price*count as total from product;

Text-handling functions:

RTrim Remove the right space

Upper to uppercase

Left returns the character

Length return string lengths

Locate find the substring of a string

Lower Turn lowercase

LTrim go to left space

Right returns the string

Soundex returns the Soundex value of the string

SUBSTRING return substring characters

(Soundex converts any text string to an algorithm that describes the alphanumeric pattern of its speech representations, taking into account similar sounds at the ego and syllable to compare strings rather than letters)

Select AVG (distinct type) from product can be used with distinct and aggregation parameters;

"MySQL must know" study notes (iii)