AlterStatement <- 'ALTER' AlterOptions


AlterOptions <- AlterTableStmt / AlterViewStmt / AlterSequenceStmt / AlterDatabaseStmt / AlterSchemaStmt

AlterTableStmt <- 'TABLE' IfExists? BaseTableName AlterTableOptions
AlterSchemaStmt <- 'SCHEMA' IfExists? QualifiedName RenameAlter

AlterTableOptions <- AddColumn / DropColumn / AlterColumn / AddConstraint / ChangeNullability / RenameColumn / RenameAlter / SetPartitionedBy / ResetPartitionedBy / SetSortedBy / ResetSortedBy

AddConstraint <- 'ADD' TopLevelConstraint
AddColumn <- 'ADD' 'COLUMN'? IfNotExists? ColumnDefinition
DropColumn <- 'DROP' 'COLUMN'? IfExists? NestedColumnName DropBehavior?
AlterColumn <- 'ALTER' 'COLUMN'? NestedColumnName AlterColumnEntry
RenameColumn <- 'RENAME' 'COLUMN'? NestedColumnName 'TO' Identifier
NestedColumnName <- (Identifier '.')* ColumnName
RenameAlter <- 'RENAME' 'TO' Identifier
SetPartitionedBy <- 'SET' 'PARTITIONED' 'BY' Parens(List(Expression))
ResetPartitionedBy <- 'RESET' 'PARTITIONED' 'BY'
SetSortedBy <- 'SET' 'SORTED' 'BY' Parens(OrderByExpressions)
ResetSortedBy <- 'RESET' 'SORTED' 'BY'

AlterColumnEntry <- AddOrDropDefault / ChangeNullability / AlterType

AddOrDropDefault <- AddDefault / DropDefault
AddDefault <- 'SET' 'DEFAULT' Expression
DropDefault <- 'DROP' 'DEFAULT'

ChangeNullability <- ('DROP' / 'SET') 'NOT' 'NULL'

AlterType <- SetData? 'TYPE' Type? UsingExpression?
SetData <- 'SET' 'DATA'?
UsingExpression <- 'USING' Expression

AlterViewStmt <- 'VIEW' IfExists? BaseTableName RenameAlter

AlterSequenceStmt <- 'SEQUENCE' IfExists? QualifiedSequenceName AlterSequenceOptions

QualifiedSequenceName <- CatalogQualification? SchemaQualification? SequenceName

AlterSequenceOptions <- RenameAlter / SetSequenceOption
SetSequenceOption <- List(SequenceOption)

AlterDatabaseStmt <- 'DATABASE' IfExists? Identifier RenameDatabaseAlter

RenameDatabaseAlter <- 'RENAME' 'TO' Identifier