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  2. SQL syntax - Wikipedia

    en.wikipedia.org/wiki/SQL_syntax

    Greater than Hire_Date > '2012-01-31' < Less than Bonus < 50000. 00 >= Greater than or equal Dependents >= 2 <= Less than or equal Rate <= 0. 05 [NOT] BETWEEN [SYMMETRIC] Between an inclusive range. SYMMETRIC inverts the range bounds if the first is higher than the second. Cost BETWEEN 100. 00 AND 500. 00 [NOT] LIKE [ESCAPE] Begins with a ...

  3. Range query (database) - Wikipedia

    en.wikipedia.org/wiki/Range_query_(database)

    A range query is a common database operation that retrieves all records where some value is between an upper and lower boundary. [1] For example, list all employees with 3 to 5 years' experience. Range queries are unusual because it is not generally known in advance how many entries a range query will return, or if it will return any at all.

  4. Relational algebra - Wikipedia

    en.wikipedia.org/wiki/Relational_algebra

    The relational algebra uses set union, set difference, and Cartesian product from set theory, and adds additional constraints to these operators to create new ones.. For set union and set difference, the two relations involved must be union-compatible—that is, the two relations must have the same set of attributes.

  5. Database normalization - Wikipedia

    en.wikipedia.org/wiki/Database_normalization

    In situations where the number of unique values of a column is far less than the number of rows in the table, column-oriented storage allow significant savings in space through data compression. Columnar storage also allows fast execution of range queries (e.g., show all records where a particular column is between X and Y, or less than X.)

  6. Check constraint - Wikipedia

    en.wikipedia.org/wiki/Check_constraint

    A check constraint is a type of integrity constraint in SQL which specifies a requirement that must be met by each row in a database table. The constraint must be a predicate. It can refer to a single column, or multiple columns of the table. The result of the predicate can be either TRUE, FALSE, or UNKNOWN, depending on the presence of NULLs.

  7. Multiple comparisons problem - Wikipedia

    en.wikipedia.org/wiki/Multiple_comparisons_problem

    The departure of the upper tail of the distribution from the expected trend along the diagonal is due to the presence of substantially more large test statistic values than would be expected if all null hypotheses were true. The red point corresponds to the fourth largest observed test statistic, which is 3.13, versus an expected value of 2.06.

  8. SQL Plus - Wikipedia

    en.wikipedia.org/wiki/SQL_Plus

    The Server Manager Command Line — a replacement of SQL*DBA — is obsolete and SQL Plus 8i and later allows the user to issue statements like STARTUP and SHUTDOWN when connected as SYSDBA. Server Manager 7.1 introduced the command CONNECT / AS SYSDBA to replace CONNECT INTERNAL. [8] SQL Plus 8i and later allows the use of CONNECT / AS SYSDBA

  9. Strict - Wikipedia

    en.wikipedia.org/wiki/Strict

    For instance, when reading the phrase "x is positive", it is not immediately clear whether x = 0 is possible, since some authors might use the term positive loosely to mean that x is not less than zero. Such an ambiguity can be mitigated by writing "x is strictly positive" for x > 0, and "x is non-negative" for x ≥ 0.