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Jack Ye
fe651ae003
The function catalogue is now real rather than a pointer. Scalar functions are listed by taxonomy -- math, string, unicode, regex, date/time, array, map, struct, crypto, type -- and the names come from what datafusion-functions 54 actually registers, not from what DataFusion documents on main. Aggregate and window pages gain the same treatment. Two things the audit corrected rather than copied. SHOW TABLES does not work. DataFusion implements it over information_schema, which this session does not enable, so it fails at plan time. It was documented as working here, on the SHOW page and in three Manage tables; all four are fixed, and the SQL overview now lists the absence alongside SHOW COLUMNS. Prepared statements are a Flight SQL protocol feature, not a PREPARE statement. A script carrying PREPARE ... AS SELECT will not run, while the same intent expressed through a client will. The new page says so rather than copying DataFusion's syntax. Every section of the Documentation tab that has a SQL counterpart now links to it -- 27 of 76 non-SQL pages, each pointing at the specific statement rather than at the reference index.
82 lines
2.7 KiB
Plaintext
82 lines
2.7 KiB
Plaintext
---
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title: "Operators and literals"
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sidebarTitle: "Operators"
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description: "Comparison, logical and arithmetic operators, literals, and precedence."
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icon: plus-minus
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keywords: ["operators", "literals", "precedence", "null", "cast", "interval"]
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---
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<Badge color="red">Enterprise</Badge> [SQL runs on a deployment.](/sql)
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The operator set is DataFusion's. This page covers what is worth knowing when
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the operands are Lance columns.
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## Comparison {#comparison}
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| --- | --- |
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| `=` `!=` `<>` `<` `<=` `>` `>=` | ordinary comparison |
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| `IS NULL` / `IS NOT NULL` | null test — `= NULL` is never true |
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| `IS DISTINCT FROM` | comparison that treats null as a value |
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| `BETWEEN a AND b` | inclusive range |
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| `IN (...)` | set membership |
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| `LIKE` / `ILIKE` | pattern match, `%` and `_` |
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| `~` `~*` `!~` | regular expression match |
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<Note>
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For keyword matching on a text column, [`contains_tokens`](/sql/scalar-functions#contains-tokens)
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is index-accelerated where `LIKE` is not. Reach for `LIKE` only when you need
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its wildcard semantics.
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</Note>
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## Logical {#logical}
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`AND`, `OR`, `NOT`. Three-valued: a comparison against null is **unknown**, and
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`NOT unknown` is still unknown. A `WHERE` clause keeps only rows where the
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predicate is true, so unknown behaves like false there — but not inside `NOT
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IN`, which is the usual place this bites. See
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[Subqueries](/sql/subqueries#in-exists).
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## Arithmetic {#arithmetic}
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`+` `-` `*` `/` `%`, with the usual precedence. String concatenation is `||`.
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<Warning>
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Arithmetic over a vector column is **list** arithmetic, not scalar arithmetic —
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a vector is a `FixedSizeList<Float32>`. When the operation you want is a
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similarity comparison, use [vector search](/search/vector-search); there is no
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SQL form for it.
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</Warning>
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## Literals {#literals}
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| --- | --- |
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| String | `'text'` — doubled quote to escape: `'it''s'` |
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| Number | `42`, `3.14` |
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| Boolean | `TRUE`, `FALSE` |
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| Null | `NULL` |
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| Date / timestamp | `DATE '2026-01-01'`, `TIMESTAMP '2026-01-01 12:00:00'` |
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| Interval | `INTERVAL '7 days'` |
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| Array | `[1, 2, 3]` |
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Identifiers are quoted with double quotes when they need to be — a reserved word
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or a name with mixed case: `SELECT "order" FROM "MyTable"`.
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## Casting {#casting}
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```sql
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SELECT CAST(identifier AS VARCHAR), identifier::VARCHAR FROM documents
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```
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Both forms work. `TRY_CAST` returns null instead of erroring on a value that
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will not convert, which is the one to use over a column you do not control.
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## Precedence {#precedence}
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Highest to lowest: `::` → unary `-` → `* / %` → `+ -` → `||` → comparison →
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`IS` → `NOT` → `AND` → `OR`.
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Parenthesize anything mixing `AND` and `OR`. `a OR b AND c` is `a OR (b AND c)`,
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which is rarely what was meant.
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