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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 . If the predicate evaluates to UNKNOWN , then the constraint is not violated and the row can be inserted or updated in the table.
In relational databases, the information schema (information_schema) is an ANSI-standard set of read-only views that provide information about all of the tables, views, columns, and procedures in a database. [1] It can be used as a source of the information that some databases make available through non-standard commands, such as:
mw-collapsible also does not require a header row in the table, as collapsible did. Tables will show the "[hide]" / "[show]" controls in the first row of the table (whether or not it is a header row), unless a table caption is present.(see § Tables with captions) Example with a header row
ParserFunctions allow for the conditional display of table rows, columns or cells (and really, just about anything else). But Parser functions have some limits. But Parser functions have some limits. Basic use
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 result set.
Reserved words in SQL and related products In SQL:2023 [3] In IBM Db2 13 [4] In Mimer SQL 11.0 [5] In MySQL 8.0 [6] In Oracle Database 23c [7] In PostgreSQL 16 [1] In Microsoft SQL Server 2022 [2]
A table (called the referencing table) can refer to a column (or a group of columns) in another table (the referenced table) by using a foreign key. The referenced column(s) in the referenced table must be under a unique constraint, such as a primary key. Also, self-references are possible (not fully implemented in MS SQL Server though [5]).
Row-level trigger: This gets executed before or after any column value of a row changes. Column-level trigger: This gets executed before or after the specified column changes. For each row type: This trigger gets executed once for each row of the result set affected by an insert/update/delete.