3/19/2023 0 Comments Drop table sqlite browser![]() CREATE INDEX com_name_collate on company (com_name COLLATE NOCASE) If you want to create a caseinsensitive index on com_name, the following index statement can be used. This means that values in the indexed column will sort without respect to the case. The COLLATE keyword is used to make a column case-insensitive associated with index. Index unique_com_id company 5 CREATE UNIQUE INDEX unique_com_id ON company( Index com_id_name company 4 CREATE INDEX com_id_name ON company (com_id,c Index com_id_index company 3 CREATE INDEX com_id_index ON company (com_id) sqlite> SELECT * FROM sqlite_master WHERE type = 'index' ![]() If you want to see database wise all indexes, use the following statement. Here is the list of indexes created on company table: sqlite>. Here in the above you can see that uniqueness is defined by both columns collectively, not individually and uniqueness is violeted here. Sqlite> INSERT INTO company VALUES ('com_001', 'company-1') Įrror: UNIQUE constraint failed: _id, _name Sqlite> INSERT INTO company VALUES ('com_002', 'company-2') Here is some examples: sqlite> INSERT INTO company VALUES ('com_001', 'company-1') In a UNIQUE index, there cannot be any duplicate entries. CREATE UNIQUE INDEX unique_com_id ON company (com_id,com_name) Īfter creating a UNIQUE index if you are trying to insert a record into the table that already exists in the UNIQUE Index, this leads to an error message. If you want to add an index named unique_com_id on com_id column of company table, the following statement can be used. This type of index is called composit index, because two or more columns collectively make this type index. Now, we want to add an index named com_id_name on the columns "com_id" and "com_name": CREATE INDEX com_id_name ON company (com_id,com_name) CREATE INDEX com_id_index ON company (com_id) Here, we added an index named com_id_index on the column "com_id" of company table. Table_name - Name of the table with which the index is associated. Syntax: CREATE INDEX index_name ON table_name ( column_name ) To prevent NULLs, you must indicate NOT NULL in the original table definition.ĭropping an index will remove the index from the database, but the associated table will remain intact. As NULL isn’t considered a value, so a UNIQUE index will not prevent one or more NULLs. Usually, the indexes can allow duplicate values, but with the UNIQUE keyword restricts the duplicity for any attempt to insert or update a table with a nonunique value. Indexes are always associated with only one table, but more columns of the table can be included in the indexes. Hence, indexes can provide a large performance boost to some types of queries. ![]() ![]() Indexes (or indices) are very special to a database lookups, because, this allows specific rows in a table to be found without having to scan every row in the table. An index is a special data structure, which stores the values for an entire column (or columns) in a highly organized manner that is optimized for searching. ![]()
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