fix for databases which don't like multiple 'check' keywords

- also check for dupe constraints (for some reason they get added)

hibernate-core/src/main/java/org/hibernate/mapping/CheckConstraint.java

@@ -6,6 +6,8 @@
  */
 package org.hibernate.mapping;
 
+import java.util.Objects;
+
 /**
  * Represents a table or column level {@code check} constraint.
  *
@@ -24,6 +26,14 @@ public class CheckConstraint {
 		this.constraint = constraint;
 	}
 
+	public boolean isNamed() {
+		return name != null;
+	}
+
+	public boolean isAnonymous() {
+		return name == null;
+	}
+
 	public String getName() {
 		return name;
 	}
@@ -36,6 +46,10 @@ public class CheckConstraint {
 		return constraint;
 	}
 
+	public String getConstraintInParens() {
+		return "(" + constraint + ")";
+	}
+
 	public void setConstraint(String constraint) {
 		this.constraint = constraint;
 	}
@@ -45,4 +59,21 @@ public class CheckConstraint {
 				? " check (" + constraint + ")"
 				: " constraint " + name + " check (" + constraint + ")";
 	}
+
+	@Override
+	public boolean equals(Object object) {
+		if ( object instanceof CheckConstraint ) {
+			CheckConstraint other = (CheckConstraint) object;
+			return Objects.equals( name, other.name )
+				&& Objects.equals( constraint, other.constraint );
+		}
+		else {
+			return false;
+		}
+	}
+
+	@Override
+	public int hashCode() {
+		return constraint.hashCode();
+	}
 }

hibernate-core/src/main/java/org/hibernate/mapping/Column.java

@@ -493,7 +493,9 @@ public class Column implements Selectable, Serializable, Cloneable, ColumnTypeIn
 	}
 
 	public void addCheckConstraint(CheckConstraint checkConstraint) {
-		this.checkConstraints.add( checkConstraint );
+		if ( !checkConstraints.contains( checkConstraint) ) {
+			checkConstraints.add( checkConstraint );
+		}
 	}
 
 	public java.util.List<CheckConstraint> getCheckConstraints() {

hibernate-core/src/main/java/org/hibernate/tool/schema/internal/ColumnDefinitions.java

@@ -19,6 +19,8 @@ import org.hibernate.mapping.UniqueKey;
 import org.hibernate.tool.schema.extract.spi.ColumnInformation;
 import org.hibernate.type.descriptor.jdbc.JdbcType;
 
+import java.util.List;
+
 class ColumnDefinitions {
 
 	static boolean hasMatchingType(Column column, ColumnInformation columnInformation, Metadata metadata, Dialect dialect) {
@@ -97,13 +99,41 @@ class ColumnDefinitions {
 		if ( column.isUnique() && !table.isPrimaryKey( column ) ) {
 			final String keyName = Constraint.generateName( "UK_", table, column);
 			final UniqueKey uniqueKey = table.getOrCreateUniqueKey( keyName );
-			uniqueKey.addColumn(column);
+			uniqueKey.addColumn( column );
 			definition.append( dialect.getUniqueDelegate().getColumnDefinitionUniquenessFragment( column, context ) );
 		}
 
 		if ( dialect.supportsColumnCheck() ) {
-			for ( CheckConstraint checkConstraint : column.getCheckConstraints() ) {
+			// some databases (Maria, SQL Server) don't like multiple 'check' clauses
-				definition.append( checkConstraint.constraintString() );
+			final List<CheckConstraint> checkConstraints = column.getCheckConstraints();
+			long anonConstraints = checkConstraints.stream().filter(CheckConstraint::isAnonymous).count();
+			if ( anonConstraints == 1 ) {
+				for ( CheckConstraint constraint : checkConstraints ) {
+					definition.append( constraint.constraintString() );
+				}
+			}
+			else {
+				boolean first = true;
+				for ( CheckConstraint constraint : checkConstraints ) {
+					if ( constraint.isAnonymous() ) {
+						if ( first ) {
+							definition.append(" check (");
+							first = false;
+						}
+						else {
+							definition.append(" and ");
+						}
+						definition.append( constraint.getConstraintInParens() );
+					}
+				}
+				if ( !first ) {
+					definition.append(")");
+				}
+				for ( CheckConstraint constraint : checkConstraints ) {
+					if ( constraint.isNamed() ) {
+						definition.append( constraint.constraintString() );
+					}
+				}
 			}
 		}
 	}