1+ using System ;
2+ using System . Data ;
3+ using System . Data . Common ;
4+ using System . Linq ;
5+ using System . Text ;
6+
7+ namespace DuckDB . NET . Data ;
8+
9+ internal static class DuckDBSchema
10+ {
11+ private static readonly string [ ] TableRestrictions = [ "table_catalog" , "table_schema" , "table_name" , "table_type" ] ;
12+
13+ private static readonly string [ ] ColumnRestrictions = [ "table_catalog" , "table_schema" , "table_name" , "column_name" ] ;
14+
15+ private static readonly string [ ] ForeignKeyRestrictions = [ "constraint_catalog" , "constraint_schema" , "table_name" , "constraint_name" ] ;
16+
17+ private static readonly string [ ] IndexesRestrictions = [ "index_catalog" , "index_schema" , "table_name" , "index_name" ] ;
18+
19+ public static DataTable GetSchema ( DuckDBConnection connection , string collectionName , string ? [ ] ? restrictionValues ) =>
20+ collectionName . ToUpperInvariant ( ) switch
21+ {
22+ "METADATACOLLECTIONS" => GetMetaDataCollections ( ) ,
23+ "RESTRICTIONS" => GetRestrictions ( ) ,
24+ "RESERVEDWORDS" => GetReservedWords ( connection ) ,
25+ "TABLES" => GetTables ( connection , restrictionValues ) ,
26+ "COLUMNS" => GetColumns ( connection , restrictionValues ) ,
27+ "FOREIGNKEYS" => GetForeignKeys ( connection , restrictionValues ) ,
28+ "INDEXES" => GetIndexes ( connection , restrictionValues ) ,
29+ _ => throw new ArgumentOutOfRangeException ( nameof ( collectionName ) , collectionName , "Invalid collection name." )
30+ } ;
31+
32+ private static DataTable GetMetaDataCollections ( ) =>
33+ new ( DbMetaDataCollectionNames . MetaDataCollections )
34+ {
35+ Columns =
36+ {
37+ { DbMetaDataColumnNames . CollectionName , typeof ( string ) } ,
38+ { DbMetaDataColumnNames . NumberOfRestrictions , typeof ( int ) } ,
39+ { DbMetaDataColumnNames . NumberOfIdentifierParts , typeof ( int ) }
40+ } ,
41+ Rows =
42+ {
43+ { DbMetaDataCollectionNames . MetaDataCollections , 0 , 0 } ,
44+ { DbMetaDataCollectionNames . Restrictions , 0 , 0 } ,
45+ { DbMetaDataCollectionNames . ReservedWords , 0 , 0 } ,
46+ { DuckDbMetaDataCollectionNames . Tables , TableRestrictions . Length , 3 } ,
47+ { DuckDbMetaDataCollectionNames . Columns , ColumnRestrictions . Length , 4 } ,
48+ { DuckDbMetaDataCollectionNames . ForeignKeys , ForeignKeyRestrictions . Length , 3 } ,
49+ { DuckDbMetaDataCollectionNames . Indexes , IndexesRestrictions . Length , 3 } ,
50+ }
51+ } ;
52+
53+ private static DataTable GetRestrictions ( ) =>
54+ new ( DbMetaDataCollectionNames . Restrictions )
55+ {
56+ Columns =
57+ {
58+ { "CollectionName" , typeof ( string ) } ,
59+ { "RestrictionName" , typeof ( string ) } ,
60+ { "RestrictionDefault" , typeof ( string ) } ,
61+ { "RestrictionNumber" , typeof ( int ) }
62+ } ,
63+ Rows =
64+ {
65+ { DuckDbMetaDataCollectionNames . Tables , "Catalog" , "table_catalog" , 1 } ,
66+ { DuckDbMetaDataCollectionNames . Tables , "Schema" , "table_schema" , 2 } ,
67+ { DuckDbMetaDataCollectionNames . Tables , "Table" , "table_name" , 3 } ,
68+ { DuckDbMetaDataCollectionNames . Tables , "TableType" , "table_type" , 4 } ,
69+
70+ { DuckDbMetaDataCollectionNames . Columns , "Catalog" , "table_catalog" , 1 } ,
71+ { DuckDbMetaDataCollectionNames . Columns , "Schema" , "table_schema" , 2 } ,
72+ { DuckDbMetaDataCollectionNames . Columns , "Table" , "table_name" , 3 } ,
73+ { DuckDbMetaDataCollectionNames . Columns , "Column" , "column_name" , 4 } ,
74+
75+ { DuckDbMetaDataCollectionNames . ForeignKeys , "Catalog" , "constraint_catalog" , 1 } ,
76+ { DuckDbMetaDataCollectionNames . ForeignKeys , "Schema" , "constraint_schema" , 2 } ,
77+ { DuckDbMetaDataCollectionNames . ForeignKeys , "Table" , "table_name" , 3 } ,
78+ { DuckDbMetaDataCollectionNames . ForeignKeys , "Constraint" , "constraint_name" , 4 } ,
79+
80+ { DuckDbMetaDataCollectionNames . Indexes , "Catalog" , "constraint_catalog" , 1 } ,
81+ { DuckDbMetaDataCollectionNames . Indexes , "Schema" , "constraint_schema" , 2 } ,
82+ { DuckDbMetaDataCollectionNames . Indexes , "Table" , "table_name" , 3 } ,
83+ { DuckDbMetaDataCollectionNames . Indexes , "Constraint" , "constraint_name" , 4 } ,
84+ } ,
85+ } ;
86+
87+ private static DataTable GetReservedWords ( DuckDBConnection connection )
88+ {
89+ using var command = connection . CreateCommand ( ) ;
90+ command . CommandText = "SELECT keyword_name as ReservedWord FROM duckdb_keywords() WHERE keyword_category = 'reserved'" ;
91+ return GetDataTable ( DbMetaDataCollectionNames . ReservedWords , command ) ;
92+ }
93+
94+ private static DataTable GetTables ( DuckDBConnection connection , string ? [ ] ? restrictionValues )
95+ {
96+ if ( restrictionValues ? . Length > TableRestrictions . Length )
97+ {
98+ throw new ArgumentException ( "Too many restrictions" , nameof ( restrictionValues ) ) ;
99+ }
100+
101+ const string query = "SELECT table_catalog, table_schema, table_name, table_type FROM information_schema.tables" ;
102+
103+ using var command = BuildCommand ( connection , query , restrictionValues , true , TableRestrictions ) ;
104+
105+ return GetDataTable ( DuckDbMetaDataCollectionNames . Tables , command ) ;
106+ }
107+
108+ private static DataTable GetColumns ( DuckDBConnection connection , string ? [ ] ? restrictionValues )
109+ {
110+ if ( restrictionValues ? . Length > ColumnRestrictions . Length )
111+ {
112+ throw new ArgumentException ( "Too many restrictions" , nameof ( restrictionValues ) ) ;
113+ }
114+
115+ const string query =
116+ """
117+ SELECT
118+ table_catalog, table_schema, table_name, column_name,
119+ ordinal_position, column_default, is_nullable, data_type,
120+ character_maximum_length, character_octet_length,
121+ numeric_precision, numeric_precision_radix,
122+ numeric_scale, datetime_precision,
123+ character_set_catalog, character_set_schema, character_set_name, collation_catalog
124+ FROM information_schema.columns
125+ """ ;
126+ using var command = BuildCommand ( connection , query , restrictionValues , true , ColumnRestrictions ) ;
127+
128+ return GetDataTable ( DuckDbMetaDataCollectionNames . Columns , command ) ;
129+ }
130+
131+ private static DataTable GetForeignKeys ( DuckDBConnection connection , string ? [ ] ? restrictionValues )
132+ {
133+ if ( restrictionValues ? . Length > ForeignKeyRestrictions . Length )
134+ {
135+ throw new ArgumentException ( "Too many restrictions" , nameof ( restrictionValues ) ) ;
136+ }
137+
138+ const string query =
139+ """
140+ SELECT
141+ constraint_catalog, constraint_schema, constraint_name,
142+ table_catalog, table_schema, table_name, constraint_type,
143+ is_deferrable, initially_deferred
144+ FROM information_schema.table_constraints
145+ WHERE constraint_type = 'FOREIGN KEY'
146+ """ ;
147+ using var command = BuildCommand ( connection , query , restrictionValues , false , ForeignKeyRestrictions ) ;
148+
149+ return GetDataTable ( DuckDbMetaDataCollectionNames . ForeignKeys , command ) ;
150+ }
151+
152+ private static DataTable GetIndexes ( DuckDBConnection connection , string ? [ ] ? restrictionValues )
153+ {
154+ if ( restrictionValues ? . Length > IndexesRestrictions . Length )
155+ {
156+ throw new ArgumentException ( "Too many restrictions" , nameof ( restrictionValues ) ) ;
157+ }
158+
159+ const string query =
160+ """
161+ SELECT
162+ database_name as index_catalog,
163+ schema_name as index_schema,
164+ index_name,
165+ table_name,
166+ is_unique,
167+ is_primary
168+ FROM duckdb_indexes()
169+ """ ;
170+ using var command = BuildCommand ( connection , query , restrictionValues , true , IndexesRestrictions ) ;
171+
172+ return GetDataTable ( DuckDbMetaDataCollectionNames . Indexes , command ) ;
173+ }
174+
175+ private static DuckDBCommand BuildCommand ( DuckDBConnection connection , string query , string ? [ ] ? restrictions , bool addWhere , string [ ] ? restrictionNames )
176+ {
177+ var command = connection . CreateCommand ( ) ;
178+ if ( restrictions is not { Length : > 0 } || restrictionNames == null )
179+ {
180+ command . CommandText = query ;
181+ return command ;
182+ }
183+
184+ var builder = new StringBuilder ( query ) ;
185+ foreach ( var ( name , restriction ) in restrictionNames . Zip ( restrictions , Tuple . Create ) )
186+ {
187+ if ( restriction ? . Length > 0 )
188+ {
189+ if ( addWhere )
190+ {
191+ builder . Append ( " WHERE " ) ;
192+ addWhere = false ;
193+ }
194+ else
195+ {
196+ builder . Append ( " AND " ) ;
197+ }
198+
199+ builder . Append ( $ "{ name } = ${ name } ") ;
200+ command . Parameters . Add ( new DuckDBParameter ( name , restriction ) ) ;
201+ }
202+ }
203+
204+ command . CommandText = builder . ToString ( ) ;
205+ return command ;
206+ }
207+
208+ private static DataTable GetDataTable ( string tableName , DuckDBCommand command )
209+ {
210+ var table = new DataTable ( tableName ) ;
211+ try
212+ {
213+ using var reader = command . ExecuteReader ( ) ;
214+ table . BeginLoadData ( ) ;
215+ table . Load ( reader ) ;
216+ }
217+ finally
218+ {
219+ table . EndLoadData ( ) ;
220+ }
221+
222+ return table ;
223+ }
224+ }
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