Sql – ny query for Cassandra as same as SQL:LIKE Condition

cassandrapycassasql

The LIKE condition allows us to use wildcards in the where clause of an SQL statement. This allows us to perform pattern matching. The LIKE condition can be used in any valid SQL statement – select, insert, update, or delete. Like this

SELECT * FROM users
WHERE user_name like 'babu%';

like the same above operation any query is available for Cassandra in CLI.

Best Answer

Since Cassandra 3.4 (3.5 recommended), LIKE queries can be achieved using a SSTable Attached Secondary Index (SASI).

For example:

CREATE TABLE cycling.cyclist_name ( 
  id UUID PRIMARY KEY, 
  lastname text, 
  firstname text
);

Creating the SASI as follows:

CREATE CUSTOM INDEX  fn_prefix ON cyclist_name (firstname)
USING 'org.apache.cassandra.index.sasi.SASIIndex';

Then a prefix LIKE query is working:

SELECT * FROM cyclist_name WHERE firstname LIKE 'M%';
SELECT * FROM cyclist_name WHERE firstname LIKE 'Mic%';

These examples and more configuration options, like suffix queries, can be found in the documentation

A more in depth explanation about how SASI works can be found here.

Related Solutions

SQLite – UPSERT not INSERT or REPLACE

Assuming three columns in the table: ID, NAME, ROLE

BAD: This will insert or replace all columns with new values for ID=1:

INSERT OR REPLACE INTO Employee (id, name, role) 
  VALUES (1, 'John Foo', 'CEO');

BAD: This will insert or replace 2 of the columns... the NAME column will be set to NULL or the default value:

INSERT OR REPLACE INTO Employee (id, role) 
  VALUES (1, 'code monkey');

GOOD: Use SQLite On conflict clause UPSERT support in SQLite! UPSERT syntax was added to SQLite with version 3.24.0!

UPSERT is a special syntax addition to INSERT that causes the INSERT to behave as an UPDATE or a no-op if the INSERT would violate a uniqueness constraint. UPSERT is not standard SQL. UPSERT in SQLite follows the syntax established by PostgreSQL.

GOOD but tedious: This will update 2 of the columns. When ID=1 exists, the NAME will be unaffected. When ID=1 does not exist, the name will be the default (NULL).

INSERT OR REPLACE INTO Employee (id, role, name) 
  VALUES (  1, 
            'code monkey',
            (SELECT name FROM Employee WHERE id = 1)
          );

This will update 2 of the columns. When ID=1 exists, the ROLE will be unaffected. When ID=1 does not exist, the role will be set to 'Benchwarmer' instead of the default value.

INSERT OR REPLACE INTO Employee (id, name, role) 
  VALUES (  1, 
            'Susan Bar',
            COALESCE((SELECT role FROM Employee WHERE id = 1), 'Benchwarmer')
          );

Sql Server equivalent of a COUNTIF aggregate function

You could use a SUM (not COUNT!) combined with a CASE statement, like this:

SELECT SUM(CASE WHEN myColumn=1 THEN 1 ELSE 0 END)
FROM AD_CurrentView

Note: in my own test NULLs were not an issue, though this can be environment dependent. You could handle nulls such as:

SELECT SUM(CASE WHEN ISNULL(myColumn,0)=1 THEN 1 ELSE 0 END)
FROM AD_CurrentView

Best Answer

Related Solutions

SQLite – UPSERT *not* INSERT or REPLACE

Sql Server equivalent of a COUNTIF aggregate function

Related Topic

SQLite – UPSERT not INSERT or REPLACE