Shulou(Shulou.com)06/01 Report--

2 specific content

2.1 scope of use

SQL Server (since 2008); Azure SQL database; Azure SQL data warehouse; parallel data warehouse

2.2 Grammar

Is a combination of symbols and operators evaluated by the SQL Server database engine to obtain a single data value. A simple expression can be a single constant, variable, column, or scalar function. Operators can be used to join two or more simple expressions into a complex expression.

-- Syntax for SQL Server and Azure SQL Database {constant | scalar_function | [table_name. ] Column | variable | (expression) | (scalar_subquery) | {unary_operator} expression | expression {binary_operator} expression | ranking_windowed_function | aggregate_windowed_function}-- Syntax for Azure SQL Data Warehouse and Parallel Data Warehouse-- Expression ina SELECT statement:: = {constant | scalar_function | column | variable | (expression) | {unary_operator} expression | expression {binary_operator} expression} [COLLATE Windows_collation_name]-Scalar Expression ina DECLARE, SET, IF … ELSE, or WHILE statement:: = {constant | scalar_function | variable | (expression) | (scalar_subquery) | {unary_operator} expression | expression {binary_operator} expression} [COLLATE {Windows_collation_name]

2.3 parameters

Translation:

2.4 expression result

For a simple expression consisting of a single constant, variable, scalar function, or column name: the data type of the expression, collation, precision, scale, and value are data types, collation, precision, scale, and value reference elements.

When you combine two expressions using comparison or logical operators, the resulting data type is Boolean, which is one of the following values: TRUE,FALSE or UNKNOWN. For more information about Boolean data types, see comparison operator (Transact-SQL).

When two expressions are combined using arithmetic, bitwise or string operators, the operator determines the type of data generated.

A complex expression consisting of many symbols and operators is evaluated as a single-valued result. Combine expressions to determine the data type, collation, precision, and value of the generated expression, two at a time, until the final result is reached. The order in which expressions are combined is defined by the precedence of operators in the expression.

2.5 remarks

3 references

[01] https://docs.microsoft.com/zh-cn/sql/t-sql/language-elements/expressions-transact-sql

Summary

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