In SQL Server, you can use the plus operator (+) to concatenate strings. However, if you need to concatenate multiple strings or fields in a table, you need to use the built-in concatenation function.

The following are some of the built-in splice functions in SQL Server:

1. CONCAT: Splice two or more strings together. The syntax is:

CONCAT (string1, string2, ...)

Example:

SELECT CONCAT('Hello', ' ', 'World') as combined_string;

输出结果为：Hello World

2. CONCAT_WS: Similar to CONCAT, but you can specify a separator. The syntax is:

CONCAT_WS (separator, string1, string2, ...)

Example:

SELECT CONCAT_WS('-', 'First', 'Second', 'Third') as combined_string;

输出结果为：First-Second-Third

3. CONCATN: Splice multiple strings together and add specified characters between each string. The syntax is:

CONCATN (separator, string1, string2, ...)

Example:

SELECT CONCATN('-', 'First', 'Second', 'Third') as combined_string;

输出结果为：First-Second-Third

4. REPLACE: used to replace the specified substring in the string. The syntax is:

REPLACE (string, old_substring, new_substring)

Example:

SELECT REPLACE('Hello World', 'World', 'SQL Server') as replaced_string;

输出结果为：Hello SQL Server

5. +: Any type of data can be converted into strings and spliced ​​together. The syntax is:

+ expression

Example:

SELECT 'Hello' + CAST(123 AS VARCHAR(10)) as combined_string;
    
输出结果为：Hello123