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https://dev.mysql.com/doc/refman/5.7/en/information-schema-columns-table.html
The COLUMNS table has these columns: TABLE_CATALOG The name of the catalog to which the table containing the column belongs. TABLE_SCHEMA The name of the schema (database) to which the table containing the column belongs. Unlike SHOW COLUMNS, SELECT ...ORDINAL_POSITION is necessary because you might want to say ORDER BY ...
https://dev.mysql.com/doc/refman/5.7/en/create-table-generated-columns.html
Values of a generated column are computed from an expression included in the column definition. Generated columns are supported by the NDB storage engine beginning with MySQL NDB Cluster 7.5.3. Generated column definitions have this syntax: col_name ...Constructs that are permitted or prohibited in the expression are discussed ...
https://dev.mysql.com/doc/refman/5.7/en/show-columns.html
SHOW [FULL] {COLUMNS | FIELDS} {FROM | IN} tbl_name [{FROM | IN} db_name] [LIKE 'pattern' | WHERE expr] SHOW COLUMNS displays information about the columns in a given table. SHOW COLUMNS displays information only for those columns for which you ...
https://dev.mysql.com/doc/refman/5.7/en/column-count-limit.html
This section describes limits on the number of columns in tables and the size of individual rows. Column Count Limits Row Size Limits Column Count Limits MySQL has hard limit of 4096 columns per table, but the effective maximum may be less for a ...
https://dev.mysql.com/doc/refman/5.7/en/partitioning-columns-list.html
This is a variant of LIST partitioning that enables the use of multiple columns as partition keys, and for columns of data types other than integer types to be used as partitioning columns; you can use string types, DATE, and DATETIME columns. In ...
https://dev.mysql.com/doc/refman/5.7/en/multiple-column-indexes.html
MySQL can create composite indexes (that is, indexes on multiple columns). For certain data types, you can index a prefix of the column (see Section 8.3.4, “Column Indexes”). MySQL can use multiple-column indexes for queries that test all the ...The index can be used for lookups in queries that specify values in a known range for combinations of last_name and first_name ...
https://dev.mysql.com/doc/refman/5.7/en/generated-column-index-optimizations.html
For example: CREATE TABLE t1 (f1 INT, gc INT AS (f1 + 1) STORED, INDEX (gc)); The generated column, gc, is defined as the expression f1 + 1. The column is also indexed and the optimizer can take that index into account during execution plan ...You ...
https://dev.mysql.com/doc/refman/5.7/en/charset-column.html
Every “character” column (that is, a column of type CHAR, VARCHAR, a TEXT type, or any synonym) has a column character set and a column collation. CREATE TABLE t1 ( col1 CHAR(10) CHARACTER SET utf8 COLLATE utf8_unicode_ci ) CHARACTER SET latin1 ...If CHARACTER SET charset_name is specified without COLLATE, character set charset_name and its default collation are ...
https://dev.mysql.com/doc/refman/5.7/en/partitioning-columns.html
The next two sections discuss COLUMNS partitioning, which are variants on RANGE and LIST partitioning. COLUMNS partitioning enables the use of multiple columns in partitioning keys. All of these columns are taken into account both for the purpose ...The permitted data types are shown in the following list: All integer types: TINYINT, SMALLINT, MEDIUMINT, INT (INTEGER), and ...
https://dev.mysql.com/doc/refman/5.7/en/column-indexes.html
The most common type of index involves a single column, storing copies of the values from that column in a data structure, allowing fast lookups for the rows with the corresponding column values. For additional information about column indexes, see ...The B-tree data structure lets the index quickly find a specific value, a set of values, or a range of values, corresponding to operators such as =, >, ≤, BETWEEN, IN, and so on, in a WHERE ...