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Spring Data Relational support
/*
* Copyright 2019-2023 the original author or authors.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* https://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.springframework.data.relational.core.sql;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collection;
import java.util.Collections;
import org.springframework.util.Assert;
/**
* Factory for common {@link Expression function expressions}.
*
* @author Mark Paluch
* @author Jens Schauder
* @since 1.1
* @see SQL
* @see Expressions
* @see Functions
*/
public class Functions {
/**
* Creates a new {@code COUNT} function.
*
* @param columns columns to apply count, must not be {@literal null}.
* @return the new {@link SimpleFunction count function} for {@code columns}.
*/
public static SimpleFunction count(Expression... columns) {
Assert.notNull(columns, "Columns must not be null!");
Assert.notEmpty(columns, "Columns must contains at least one column");
return SimpleFunction.create("COUNT", Arrays.asList(columns));
}
/**
* Creates a new {@code COUNT} function.
*
* @param columns columns to apply count, must not be {@literal null}.
* @return the new {@link SimpleFunction count function} for {@code columns}.
*/
public static SimpleFunction count(Collection columns) {
Assert.notNull(columns, "Columns must not be null!");
return SimpleFunction.create("COUNT", new ArrayList<>(columns));
}
/**
* Creates a new {@code UPPER} function.
*
* @param expression expression to apply count, must not be {@literal null}.
* @return the new {@link SimpleFunction upper function} for {@code expression}.
* @since 2.0
*/
public static SimpleFunction upper(Expression expression) {
Assert.notNull(expression, "Expression must not be null!");
return SimpleFunction.create("UPPER", Collections.singletonList(expression));
}
/**
* Creates a new {@code LOWER} function.
*
* @param expression expression to apply lower, must not be {@literal null}.
* @return the new {@link SimpleFunction lower function} for {@code expression}.
* @since 2.0
*/
public static SimpleFunction lower(Expression expression) {
Assert.notNull(expression, "Columns must not be null!");
return SimpleFunction.create("LOWER", Collections.singletonList(expression));
}
// Utility constructor.
private Functions() {}
}