When generating table alias names, if the column in a @Where clause starts with an underscore, then the alias for the table is omitted from the query.

@Entity
@Table(name = "header")
public class Header {
	@Id
	private Integer id;
	@OneToMany(fetch=FetchType.EAGER)
	@JoinColumn(name="header_id", referencedColumnName="id")
	@Where(clause="column2 = '13' and _column1 = '13'")
	private Set<Line> lines;
}

@Entity
@Table(name = "line")
public class Line {
	@Id
	private Integer id;
	private Integer header_id;
	private String _column1;
	private String column2;
}

EntityManager em = managerFactory.createEntityManager();
em.find(Header.class, 1);

Generated query:

Hibernate:
select
header0_.id as id1_0_0_,
lines1_.header_id as header_i4_1_1_,
lines1_.id as id1_1_1_,
lines1_.id as id1_1_2_,
lines1_.column1 as _column2_1_2,
lines1_.column2 as column3_1_2_,
lines1_.header_id as header_i4_1_2_
from
header header0_
left outer join
line lines1_
on header0_.id=lines1_.header_id
and (
lines1_.column2 = '13'
and _column1 = '13'
)
where
header0_.id=?

Column column1 is missing the lines1 alias.

Where this is really a problem is when you have a relationship like the following:

@Entity
@Table(name = "header")
public class Header {
	@Id
	private Integer id;
	
	@OneToMany(fetch=FetchType.EAGER)
	@JoinColumn(name="header_id", referencedColumnName="id")
	@Where(clause="_column1 = '14'")
	private Set<Line> lines;
	
	@OneToMany(fetch=FetchType.EAGER)
	@JoinColumn(name="header_id", referencedColumnName="id")
	@Where(clause="_column1 = '13'")
	private Set<OtherLine> otherLines;
}

@Entity
@Table(name = "line")
public class Line {
	@Id
	private Integer id;
	private Integer header_id;
	private String _column1;
	private String column2;
}

@Entity
@Table(name = "otherline")
public class OtherLine {
	@Id
	private Integer id;
	private Integer header_id;
	private String _column1;
	private String column2;
}

Generated query:

Hibernate:
select
header0_.id as id1_0_0_,
lines1_.header_id as header_i4_1_1_,
lines1_.id as id1_1_1_,
lines1_.id as id1_1_2_,
lines1_.column1 as _column2_1_2,
lines1_.column2 as column3_1_2_,
lines1_.header_id as header_i4_1_2_,
otherlines2_.header_id as header_i4_2_3_,
otherlines2_.id as id1_2_3_,
otherlines2_.id as id1_2_4_,
otherlines2_.column1 as _column2_2_4,
otherlines2_.column2 as column3_2_4_,
otherlines2_.header_id as header_i4_2_4_
from
header header0_
left outer join
line lines1_
on header0_.id=lines1_.header_id
and (
_column1 = '14'
)
left outer join
otherline otherlines2_
on header0_.id=otherlines2_.header_id
and (
_column1 = '13'
)
where
header0_.id=?

Both _column1 are missing their alias and cause the following exception:

SQL error or missing database (ambiguous column name: _column1)

Most people don't use underscore's in their table names. I am working with a database where ALL primary keys to the tables start with underscore and I have to jump through modeling hoops in order to get these to work.

Please see the github repository dedicated to this issue with multiple examples:

https://github.com/oblodgett/HibernateHelloWorld

This issue might be linked to HHH-2022 Closed , and HHH-3727 Closed but seems to be a distinct issue on its own.