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env is a shell command for Unix and Unix-like operating systems. It is used to either print a list of environment variables or run another utility in an altered environment without having to modify the currently existing environment. Using env, variables may be added or removed, and existing variables may be changed by assigning new values to them.
Standard environment variables or reserved environment variables include: %APPEND% (supported since DOS 3.3) This variable contains a semicolon-delimited list of directories in which to search for files. It is usually changed via the APPEND /E command, which also ensures that the directory names are converted into uppercase.
The following example of a SELECT query returns a list of expensive books. The query retrieves all rows from the Book table in which the price column contains a value greater than 100.00. The result is sorted in ascending order by title. The asterisk (*) in the select list indicates that all columns of the Book table should be included in the ...
cmd.exe in Windows NT 2000, 4DOS, 4OS2, 4NT, and a number of third-party solutions allow direct entry of environment variables from the command prompt. From at least Windows 2000, the set command allows for the evaluation of strings into variables, thus providing inter alia a means of performing integer arithmetic.
Major DBMSs, including SQLite, [5] MySQL, [6] Oracle, [7] IBM Db2, [8] Microsoft SQL Server [9] and PostgreSQL [10] support prepared statements. Prepared statements are normally executed through a non-SQL binary protocol for efficiency and protection from SQL injection, but with some DBMSs such as MySQL prepared statements are also available using a SQL syntax for debugging purposes.
An MS-DOS command line, illustrating parsing into command and arguments. A command-line argument or parameter is an item of information provided to a program when it is started. [23] A program can have many command-line arguments that identify sources or destinations of information, or that alter the operation of the program.
SQL was initially developed at IBM by Donald D. Chamberlin and Raymond F. Boyce after learning about the relational model from Edgar F. Codd [12] in the early 1970s. [13] This version, initially called SEQUEL (Structured English Query Language), was designed to manipulate and retrieve data stored in IBM's original quasirelational database management system, System R, which a group at IBM San ...
Command Prompt, also known as cmd.exe or cmd, is the default command-line interpreter for the OS/2, [1] eComStation, ArcaOS, Microsoft Windows (Windows NT family and Windows CE family), and ReactOS [2] operating systems. On Windows CE .NET 4.2, [3] Windows CE 5.0 [4] and Windows Embedded CE 6.0 [5] it is referred to as the Command Processor ...