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Important SQL server functions - string utilities

2022-07-28 04:24:00 【Navicat China】

The first 1 part ： String Utility

Every programming language seems to have some functions . Even though SQL In many ways with typical process programming languages （ for example C# or Java） Somewhat different , But it also comes with impressive built-in functions . These can be applied to CHAR、VARCHAR and TEXT data type . Each database vendor's function implementation is not exactly the same , therefore , It is worthwhile to be familiar with the functions specific to the database you are using . In this series , We will learn from SQL Server Realize some important SQL function . Today's article will discuss string functions , And the following article will discuss numbers 、 Date functions and so on ！

LEN

One of the most useful string functions is a function that calculates characters （ Including spaces and punctuation ） Quantity function that returns the length of the string . In Microsoft products , This function has been called “LEN”. This is the signature of the function ：

LEN(inputString)

for example , We will use Navicat for SQL Server As our database client , Yes Sakila The sample database performs a real query . The query is from film Select the top in descending order in the table 10 The longest Title ：

TRIM

Want to remove some useless characters from the string ？ that TRIM Function is very suitable for you ！ It eliminates redundant spaces and tabs at the beginning and end of the string we pass as parameters . This is a TRIM The signature of the ：

TRIM(inputString)

By comparing the length of the cropped title with the current length , We can use TRIM To find out whether our movie title contains leading or trailing spaces ：

CONCAT

In programming , The combination of strings is called concatenation . therefore ,CONCAT Function combines two or more strings that we pass in as parameters . This is its signature ：

CONCAT(string1, string2, ...., string_n)

CONCAT Functions are very useful , Format multiple columns together in a way that suits you and your users . The following query combines the ID、 Title and year of issue , And use commas to separate them ：

UPPER and LOWER

These two equivalent functions take a string parameter and return the same string , But all its characters are converted to uppercase and lowercase respectively .

UPPER(inputString)

To show UPPER and LOWER The effect of the function , We can display the movie title in original case , And change it through each function ：

stay Navicat Using functions in

Navicat Of SQL One of the functions of the editor is to automatically complete the code . Once you start typing words , A series of suggestions will appear , It contains all database objects , Including patterns 、 surface 、 View 、 Column 、 The process , Of course, there are function names ：

Select function （ Or stored procedure ） after , The input parameters are highlighted for input . If you have more than one parameter , Then each parameter can pass TAB Key focused , For quick access to ：

summary

In the first part of this series “ Important SQL Server function ” in , We introduced several useful string utility functions , Include LEN、TRIM、CONCAT、UPPER and LOWER. The next time , We will introduce numerical functions . If you are right about Navicat for SQL Server Interested in , Free trial 14 God .