What is Hibernate's Criteria Query?

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Criteria Query encapsulates the data query condition into an object through object-oriented design. To put it simply, Criteria Query can be seen as an object representation of traditional SQL, such as:

Criteria criteria=session.createCriteria (TUser.class); criteria.add (Expression.eq ("name", "Erica")); criteria.add (Expression.eq ("sex", new Integer (1))

The criteria instance here is essentially an encapsulation of SQL "select * from t_user where name='Erica' and sex=1". At run time, Hibernate generates the corresponding SQL statement based on the query criteria specified in Criteria.

Criteria query expression: Criteria itself is just a container, and the specific query conditions are added to the Criteria instance through the Criteria.add method.

Method description: Expression.eq corresponds to SQL "field=value" expression

For example, Expression.eq ("name", "Erica")

The Expression.allEq parameter is a Map object that contains multiple attribute-value relationships. Superimposed Expression.gt corresponding to multiple Expression.eq relationships corresponds to SQL "field > value" expression Expression.ge corresponds to SQL "field > = value" expression Expression.lt corresponds to SQL "fieldfield" Expression.gtProperty is used to compare values between two attributes, corresponding SQL "field > = field" Expression.ltProperty is used to compare values between two attributes, and corresponds to SQL "field"