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In SQL, the TRUNCATE TABLE statement is a data manipulation language (DML) [1] operation that deletes all rows of a table without causing a triggered action. The result of this operation quickly removes all data from a table, typically bypassing a number of integrity enforcing mechanisms.
Does not free the space occupied by the data in the table (in the TABLESPACE) Does not reset the SEQUENCE value assigned to the table; DELETE works much slower than TRUNCATE; You can undo the operation of removing records by using the ROLLBACK command; DELETE requires a shared table lock; Triggers fire; DELETE can be used in the case of ...
Each column in an SQL table declares the type(s) that column may contain. ANSI SQL includes the following data types. [14] Character strings and national character strings. CHARACTER(n) (or CHAR(n)): fixed-width n-character string, padded with spaces as needed; CHARACTER VARYING(n) (or VARCHAR(n)): variable-width string with a maximum size of n ...
Compressed dump files are significantly compressed, thus after being decompressed will take up large amounts of drive space. A large list of decompression programs are described in comparison of file archivers. The following programs in particular can be used to decompress bzip2, .bz2, .zip, and .7z files. Windows
(A database segment is a database object which occupies physical space such as table data and indexes.) Once created, a tablespace can be referred to by name when creating database segments. Once created, a tablespace can be referred to by name when creating database segments.
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The search space can become quite large depending on the complexity of the SQL query. There are two types of optimization. These consist of logical optimization—which generates a sequence of relational algebra to solve the query—and physical optimization—which is used to determine the means of carrying out each operation.
A common table expression, or CTE, (in SQL) is a temporary named result set, derived from a simple query and defined within the execution scope of a SELECT, INSERT, UPDATE, or DELETE statement. CTEs can be thought of as alternatives to derived tables ( subquery ), views , and inline user-defined functions.