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Exists methods

Definition​

The Exists methods allow you to add the EXISTS operator to the query.

The methods available are:

Normal method nameSQL to generate
existsEXISTS (subquery)
notExistsNOT EXISTS (subquery)
info

To use Exists methods, you need to import the static functions as follows:

import static com.myzlab.k.KFunction.*;

1. exists​

SQL to generate
EXISTS (subquery)

This method takes a single parameter and the possible value is:

KQuery.

Example: exists(KQuery)​

Java code:

final KQuery subquery = 
    k
    .select1()
    .from(APP_USER_SPECIALTY)
    .where(APP_USER.ID.eq(APP_USER_SPECIALTY.APP_USER_ID));

k
.select(APP_USER.ID)
.from(APP_USER)
.where(exists(subquery))
.multiple();

SQL generated:

SELECT au.id
FROM app_user au
WHERE EXISTS (
    SELECT ?1
    FROM app_user_specialty aus
    WHERE au.id = aus.app_user_id
)

Parameters:

  • ?1: 1

2. notExists​

SQL to generate
NOT EXISTS (subquery)

This method takes a single parameter and the possible value is:

KQuery.

Example: notExists(KQuery)​

Java code:

final KQuery subquery = 
    k
    .select1()
    .from(APP_USER_SPECIALTY)
    .where(APP_USER.ID.eq(APP_USER_SPECIALTY.APP_USER_ID));

k
.select(APP_USER.ID)
.from(APP_USER)
.where(notExists(subquery))
.multiple();

SQL generated:

SELECT au.id
FROM app_user au
WHERE NOT EXISTS (
    SELECT ?1
    FROM app_user_specialty aus
    WHERE au.id = aus.app_user_id
)

Parameters:

  • ?1: 1