ORM：DDL 与 Surface Map
模式 DDL 构造器与 orm 包的完整公开接口面。
DDL 操作
创建表
_, err := db.NewCreateTable().
Model((*User)(nil)).
IfNotExists().
Exec(ctx)
创建索引
_, err := db.NewCreateIndex().
Model((*User)(nil)).
Index("idx_user_email").
Column("email").
Unique().
IfNotExists().
Exec(ctx)
其他 DDL
db.NewDropTable().Model((*User)(nil)).IfExists().Exec(ctx)
db.NewTruncateTable().Model((*User)(nil)).Exec(ctx)
db.NewAddColumn().Model((*User)(nil)).
Column("phone", orm.DataType.Varchar(20)).
IfNotExists().
Exec(ctx)
db.NewDropColumn().Model((*User)(nil)).Column("phone").Exec(ctx)
ORM 公开 Surface Map
orm 包有意重新导出了应用代码会用到的底层 query-builder 契约：
共享的 QueryBuilder contract 公开 QueryBuilder.DB()，用于返回创建当前
query 的 VEF orm.DB；它还包含 dialect、table metadata、expression-builder、
subquery 和 condition-builder helpers。
| API 组 | 公开 surface |
|---|---|
| 数据库入口 | DB, Tx, Executor, RawQuery, SelectQuery, InsertQuery, UpdateQuery, DeleteQuery, MergeQuery, CreateTableQuery, DropTableQuery, CreateIndexQuery, DropIndexQuery, TruncateTableQuery, AddColumnQuery, DropColumnQuery, TableTarget, QueryBuilder |
| Bun/schema alias | BunSelectQuery, BunInsertQuery, BunUpdateQuery, BunDeleteQuery, Table, Field, Relation, Dialect |
| 模型基类 | BaseModel, Model, CreationAuditedModel, FullAuditedModel, CreationTrackedModel, FullTrackedModel |
| hook | BeforeSelectHook, AfterSelectHook, BeforeInsertHook, AfterInsertHook, BeforeUpdateHook, AfterUpdateHook, BeforeDeleteHook, AfterDeleteHook, BeforeScanRowHook, AfterScanRowHook |
| 核心 builder | ConditionBuilder, ExprBuilder, OrderBuilder, CaseBuilder, CaseWhenBuilder, ConflictBuilder, ConflictAction, ConflictUpdateBuilder, MergeWhenBuilder, MergeUpdateBuilder, MergeInsertBuilder, RelationSpec |
| aggregate builder | CountBuilder, SumBuilder, AvgBuilder, MinBuilder, MaxBuilder, StringAggBuilder, ArrayAggBuilder, StdDevBuilder, VarianceBuilder, JSONObjectAggBuilder, JSONArrayAggBuilder, BitOrBuilder, BitAndBuilder, BoolOrBuilder, BoolAndBuilder |
| window builder | WindowCountBuilder, WindowSumBuilder, WindowAvgBuilder, WindowMinBuilder, WindowMaxBuilder, WindowStringAggBuilder, WindowArrayAggBuilder, WindowStdDevBuilder, WindowVarianceBuilder, WindowJSONObjectAggBuilder, WindowJSONArrayAggBuilder, WindowBitOrBuilder, WindowBitAndBuilder, WindowBoolOrBuilder, WindowBoolAndBuilder, RowNumberBuilder, RankBuilder, DenseRankBuilder, PercentRankBuilder, CumeDistBuilder, NTileBuilder, LagBuilder, LeadBuilder, FirstValueBuilder, LastValueBuilder, NthValueBuilder |
| DDL builder 与类型 | DataTypeDef, ColumnConstraint, RawDefault, PrimaryKeyBuilder, UniqueBuilder, CheckBuilder, ForeignKeyBuilder, ReferenceAction, IndexMethod, PartitionStrategy |
| 表达式占位符 | PlaceholderKeyOperator, ExprOperator, ExprTableColumns, ExprColumns, ExprTablePKs, ExprPKs, ExprTableName, ExprTableAlias |
| 审计常量 | ColumnID, ColumnCreatedAt, ColumnUpdatedAt, ColumnCreatedBy, ColumnUpdatedBy, ColumnCreatedByName, ColumnUpdatedByName, FieldID, FieldCreatedAt, FieldUpdatedAt, FieldCreatedBy, FieldUpdatedBy, FieldCreatedByName, FieldUpdatedByName, OperatorSystem, OperatorCronJob, OperatorAnonymous |
| enum family | JoinType, FuzzyKind, NullsMode, FromDirection, FrameType, FrameBoundKind, StatisticalMode, DateTimeUnit, JoinDefault, JoinInner, JoinLeft, JoinRight, JoinFull, JoinCross, FuzzyStarts, FuzzyEnds, FuzzyContains, NullsDefault, NullsRespect, NullsIgnore, FromDefault, FromFirst, FromLast, FrameDefault, FrameRows, FrameRange, FrameGroups, FrameBoundNone, FrameBoundUnboundedPreceding, FrameBoundUnboundedFollowing, FrameBoundCurrentRow, FrameBoundPreceding, FrameBoundFollowing, StatisticalDefault, StatisticalPopulation, StatisticalSample, ConflictDoNothing, ConflictDoUpdate, UnitYear, UnitMonth, UnitDay, UnitHour, UnitMinute, UnitSecond, ReferenceCascade, ReferenceRestrict, ReferenceSetNull, ReferenceSetDefault, ReferenceNoAction, IndexBTree, IndexHash, IndexGIN, IndexGiST, IndexSPGiST, IndexBRIN, PartitionRange, PartitionList, PartitionHash |
| helper | Applier, ApplyFunc, ApplySort, DataType, PrimaryKey, NotNull, Nullable, Default, Unique, Check, References, AutoIncrement, PKField, ColumnInfo |
只有 DDL default 必须原样渲染可信 SQL 表达式时，才使用
orm.RawDefault("CURRENT_TIMESTAMP")。普通 orm.Default(value) 仍让字符串、
布尔值和数字走安全的 literal/bound-value 路径。