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KSQL

Operators

Comparison

Operator Description Example
= Equal to WHERE Status = 'active'
!= or <> Not equal to WHERE Status != 'churned'
> Greater than WHERE Revenue > 50000
< Less than WHERE Revenue < 1000
>= Greater than or equal WHERE Revenue >= 50000
<= Less than or equal WHERE Revenue <= 1000
IN Matches any value in list WHERE Status IN ('a', 'b')
NOT IN Does not match any value WHERE Status NOT IN ('a', 'b')
BETWEEN Within a range (inclusive) WHERE Revenue BETWEEN 10000 AND 50000
NOT BETWEEN Outside a range WHERE Revenue NOT BETWEEN 0 AND 100
LIKE Pattern match (% = any chars, _ = one char) WHERE Name LIKE '%Tech%'
NOT LIKE Does not match pattern WHERE Name NOT LIKE '%test%'
IS NULL Value is null WHERE Website IS NULL
IS NOT NULL Value is not null WHERE Website IS NOT NULL

Logical

Operator Description Example
AND Both conditions must be true WHERE a > 1 AND b < 10
OR Either condition must be true WHERE a > 1 OR b < 10
NOT Negates a condition WHERE NOT Status = 'deleted'
( ) Group conditions WHERE (a OR b) AND c

Arithmetic

Operator Description Example
+ Addition SELECT price + tax
- Subtraction SELECT revenue - costs
* Multiplication SELECT price * quantity
/ Division SELECT total / count
|| String concatenation SELECT first || ' ' || last

Array operators (CONTAINS family)

For columns that hold multiple values (tags, multi-select), use CONTAINS to filter by array membership.

Operator Description
CONTAINS value Array includes the value
CONTAINS ANY (a, b, ...) Array includes at least one of the listed values
CONTAINS ALL (a, b, ...) Array includes every listed value
CONTAINS ONLY (a, b, ...) Array contains exactly these values and nothing else
NOT CONTAINS value Array does not include the value
NOT CONTAINS ANY (a, b, ...) Array does not include any of the listed values
NOT CONTAINS ALL (a, b, ...) Array does not include all of the listed values simultaneously 
-- Row has a specific tag
WHERE Tags CONTAINS 'urgent'

-- Row has ANY of these tags (at least one match)
WHERE Tags CONTAINS ANY ('urgent', 'high-priority', 'escalated')

-- Row has ALL of these tags (every value must be present)
WHERE Tags CONTAINS ALL ('frontend', 'bug', 'p1')

-- Row has EXACTLY these tags (no more, no less)
WHERE Tags CONTAINS ONLY ('frontend', 'bug')

-- Negation
WHERE Tags NOT CONTAINS 'spam'
WHERE Tags NOT CONTAINS ANY ('spam', 'test', 'duplicate')

CONTAINS only works on array-type columns (tags, multi-select). Using it on a text or number column won't produce meaningful results.

Operator precedence

KSQL follows standard SQL precedence:

  1. Parentheses ( )
  2. Unary minus, NOT
  3. Multiplicative: *, /, ||
  4. Additive: +, -
  5. Comparison: =, !=, <, >, <=, >=, LIKE, IN, BETWEEN, IS NULL, CONTAINS
  6. Logical AND
  7. Logical OR

When in doubt, add parentheses — they cost nothing and make intent obvious.

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