Oracle does not index table rows in which all key columns are null except in the case of bitmap indexes. Therefore, if you want an index on all rows of a table, then you must either specifyNOTNULLconstraints for the index key columns or create a bitmap index. Restrictions on Bitmap I...
CREATE INDEXTYPESyntax create_index::= Description of the illustration create_index.eps (cluster_index_clause::=, table_index_clause::=, bitmap_join_index_clause::=) cluster_index_clause::= Description of the illustration cluster_index_clause.eps (index_attributes::=) table...
CREATE INDEX index_name ON table_name (column1, column2, ...); CREATE UNIQUE INDEX SyntaxCreates a unique index on a table. Duplicate values are not allowed:CREATE UNIQUE INDEX index_name ON table_name (column1, column2, ...);
);-- create indexCREATEINDEXcollege_indexONColleges(college_code); Here, the SQL command creates an index namedcollege_indexon theCollegestable using thecollege_codecolumn. SQL CREATE INDEX Syntax The syntax of the SQLCREATE INDEXstatement is: CREATEINDEXindex_nameONtable_name (column_name1, colu...
MySQL 创建索引(Create Index)的方法和语法结构及例子 CREATE INDEX Syntax CREATE [UNIQUE|FULLTEXT|SPATIAL] INDEX index_name [index_type] ON tbl_name (index_col_name,...) [index_type] index_col_name: col_name [(length)] [ASC | DESC] ...
CREATE TABLESyntax CREATE [TEMPORARY] TABLE [IF NOT EXISTS] tbl_name [(create_definition,...)] [table_options] [select_statement] create_definition: col_name type [NOT NULL | NULL] [DEFAULT default_value] [AUTO_INCREMENT] [PRIMARY KEY] [reference_definition] or PRIMARY KEY (index_col_nam...
For string columns, indexes can be created that use only the leading part of column values, using col_name(length) syntax to specify an index prefix length: Prefixes can be specified for CHAR, VARCHAR, BINARY, and VARBINARY key parts. Prefixes must be specified for BLOB and TEXT key par...
For string columns, indexes can be created that use only the leading part of column values, usingcol_name(length)syntax to specify an index prefix length: Prefixes can be specified forCHAR,VARCHAR,BINARY, andVARBINARYkey parts. Prefixesmustbe specified forBLOBandTEXTkey parts. Additionally,BLOBand...
An example in the next section illustrates the syntax. Field definitions The following attributes can be set on a field when creating an index. Expand table AttributeDescription name Required. Sets the name of the field, which must be unique within the fields collection of the index or ...
managed system identity. Properties ofaccessCredentialsincludeapplicationId(Microsoft Entra ID application ID that was granted access permissions to your specified Azure Key Vault), andapplicationSecret(authentication key of the registered application). An example in the next section illustrates the syntax. ...