importsqlite3# 自定义聚合函数defcustom_concat(values):return', '.join(values)# 连接 SQLite 数据库conn = sqlite3.connect(':memory:') conn.create_aggregate("custom_concat",1, custom_concat)# 示例查询conn.execute(''' CREATE TABLE users ( id INTEGER PRIMARY KEY, name TEXT ); INSERT INTO us...
| 0 | SELECT STATEMENT | | 1 | 2057M (5)|999:59:59 | | | | | 1 | SORT AGGREGATE | | 1 | | | | | | |* 2 | COUNT STOPKEY | | | | | | | | | 3 | PX COORDINATOR | | | | | | | | | 4 | PX SEND QC (RANDOM) | :TQ10001 | 23T| 2057M (5)|999:59:59...
在C#代码中使用存储过程也很简单: string connectionString = "..."; using (SqlConnection connection = new SqlConnection(connectionString)) { string sql = "dbo.GetBook"; using (SqlCommand cmd = new SqlCommand(sql, connection)) { cmd.CommandType = CommandType.StoredProcedure; cmd.Parameters.Add(ne...
sqlite_create_aggregate —— Register an aggregating UDF for use in SQL statements。 sqlite_create_function —— Registers a "regular" User Defined Function for use in SQL statements。 sqlite_current —— 在返回的数组中取得当前的行(the current row from a result set as an array)。 sqlite_erro...
Creates or redefines an aggregate SQL function. CreateAggregate<T1,T2,T3,T4,T5,T6,T7,T8,T9,T10,T11,T12,T13,T14, TAccumulate,TResult>(String, TAccumulate, Func<TAccumulate,T1, T2,T3,T4,T5,T6,T7,T8,T9,T10,T11,T12,T13,T14,TAccumulate>, Func<TAccumulate, TResult>, Boolean) ...
("setCustomAggregateFunction","(Ljava/lang/String;Ljava/util/function/BinaryOperator;)V","GetSetCustomAggregateFunction_Ljava_lang_String_Ljava_util_function_BinaryOperator_Handler", ApiSince=30)]publicvirtualvoidSetCustomAggregateFunction(stringfunctionName, Java.Util.Functions.IBinaryOperator aggregate...
ReplaceOrThrow(String, String, ContentValues) Convenience method for replacing a row in the database. SetCustomAggregateFunction(String, IBinaryOperator) Register a custom aggregate function that can be called from SQL expressions. SetCustomScalarFunction(String, IUnaryOperator) Register a custom scal...
sqlite3pp::ext::aggregate aggr(db); aggr.create("aggr0", &step, &finalize); struct mycnt{ void step() { ++n_; } int finish() {return n_; } int n_; }; aggr.create<mycnt>("aggr1"); struct strcnt{ void step(string const& s) { ...
聚合函数为查询中的所有行返回单个聚合值。 使用CreateAggregate定义和重写聚合函数。 seed参数指定上下文的初始状态。 使用它也可以避免闭包。 在每行调用一次func参数。 使用上下文来累积最终结果。 返回上下文。 此模式允许上下文是值类型或不可变的。 如果未指定resultSelector,则将上下文的最终状态用作结果。 这可以...
(int*) c.aggregate_data(sizeof(int)); *sum += c.get<int>(0); }voidfinalize(sqlite3pp::ext::context& c) {int* sum = (int*) c.aggregate_data(sizeof(int)); c.result(*sum); } sqlite3pp::databasedb("foods.db"); sqlite3pp::ext::aggregateaggr(db); aggr.create("aggr0",...