The jOOQ User Manual SQL building Table expressions Common table expressions (CTE)

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Common table expressions (CTE)

Supported by ✅ Open Source Edition   ✅ Express Edition   ✅ Professional Edition   ✅ Enterprise Edition

Common table expressions are table variables that are declared in the WITH clause of a DML statement for multiple use within the query.

When using common table expressions with jOOQ, there are essentially two approaches:

• Declaring and assigning common table expressions explicitly to names
• Inlining common table expressions into a SELECT statement

Explicit common table expressions

The following example makes use of names to construct common table expressions, which can then be supplied to a WITH clause or a FROM clause of a SELECT statement:

-- Pseudo-SQL for a common table expression specification
"t1" ("f1", "f2") AS (SELECT 1, 'a')

// Code for creating a CommonTableExpression instance
name("t1").fields("f1", "f2").as(select(val(1), val("a")));

The above expression can be assigned to a variable in Java and then be used to create a full SELECT statement:

WITH "t1" ("f1", "f2") AS (SELECT 1, 'a'),
     "t2" ("f3", "f4") AS (SELECT 2, 'b')
SELECT
    "t1"."f1" + "t2"."f3" AS "add",
    "t1"."f2" || "t2"."f4" AS "concat"
FROM "t1", "t2"
;

CommonTableExpression<Record2<Integer, String>> t1 =
  name("t1").fields("f1", "f2").as(select(val(1), val("a")));
CommonTableExpression<Record2<Integer, String>> t2 =
  name("t2").fields("f3", "f4").as(select(val(2), val("b")));

Result<?> result2 =
create.with(t1)
      .with(t2)
      .select(
          t1.field("f1").add(t2.field("f3")).as("add"),
          t1.field("f2").concat(t2.field("f4")).as("concat"))
      .from(t1, t2)
      .fetch();

Note that the org.jooq.CommonTableExpression type extends the commonly used org.jooq.Table type, and can thus be used wherever a table can be used.

Inlined common table expressions

If you're just operating on plain SQL, you may not need to keep intermediate references to such common table expressions. An example of such usage would be this:

WITH "a" AS (SELECT
               1 AS "x",
               'a' AS "y"
            )
SELECT
FROM "a"
;

create.with("a").as(select(
                        val(1).as("x"),
                        val("a").as("y")
                   ))
      .select()
      .from(table(name("a")))
      .fetch();

The jOOQ User Manual SQL building Table expressions Common table expressions (CTE)

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