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使用SQLite C API时,您准备声明:
sqlite3_stmt* statement; sqlite3_prepare_v2( database_handle_pointer,"SELECT * FROM table WHERE user_id=:id;",-1,&statement,NULL );
然后将值绑定到:id占位符,执行语句并逐步执行结果:
const sqlite3_int64 user_id = some_function_that_returns_a_user_id(); const int index = sqlite3_bind_parameter_index( statement,":id" ); sqlite3_bind_int64( statement,index,user_id ); while ( sqlite3_step( statement ) == sqlITE_ROW ) { // Do something with the row }
我如何使用SOCI进行此操作?看起来准备和绑定概念不像原生sqlite API那样分开.在使用soci :: use()准备期间是否必须发生绑定?
更新1:如果我没有充分解释这个问题:这是一个使用sqlite C API的小型工作C示例.如果我能看到这个使用SOCI重新实现,它将回答这个问题.
#include <sqlite3.h> #include <iostream> // Tables and data const char* table = "create table test ( @R_772_9004@id integer,name CHAR );"; const char* hank = "INSERT INTO test (user_id,Name) VALUES(1,'Hank');"; const char* bill = "INSERT INTO test (user_id,Name) VALUES(2,'Bill');"; const char* fred = "INSERT INTO test (user_id,Name) VALUES(3,'Fred');"; // Create a sqlite prepared statement to SELEct a user from the test table. sqlite3_stmt* make_statement( sqlite3* database ) { sqlite3_stmt* statement; sqlite3_prepare_v2( database,"SELECT name FROM test WHERE user_id=:id;",NULL ); return statement; } // Bind the requested user_id to the prepared statement. void bind_statement( sqlite3_stmt* statement,const sqlite3_int64 user_id ) { const int index = sqlite3_bind_parameter_index( statement,":id" ); sqlite3_bind_int64( statement,user_id ); } // Execute the statement and print the name of the SELEcted user. void execute_statement( sqlite3_stmt* statement ) { while ( sqlite3_step( statement ) == sqlITE_ROW ) { std::cout << sqlite3_column_text( statement,0 ) << "\n"; } } int main() { // Create an in-memory database. sqlite3* database; if ( sqlite3_open( ":memory:",&database ) != sqlITE_OK ) { std::cerr << "Error creaTing database" << std::endl; return -1; } // Create a table and some rows. sqlite3_exec( database,table,NULL,NULL ); sqlite3_exec( database,hank,bill,fred,NULL ); sqlite3_stmt* statement = make_statement( database ); bind_statement( statement,2 ); execute_statement( statement ); // Cleanup sqlite3_finalize( statement ); sqlite3_close( database ); return 1; }
使用SOCI部分实现相同的程序(注意标记为HelPME的两个存根函数)
#include <soci/soci.h> #include <iostream> const char* table = "create table test ( @R_772_9004@id integer,'Fred');"; soci::statement make_statement( soci::session& database ) { soci::statement statement = database.prepare << "SELECT name FROM test WHERE user_id=:id"; return statement; } void bind_statement( soci::statement& statement,const int user_id ) { // HelPME: what goes here? } void execute_statement( soci::statement& statement ) { // HelPME: what goes here? } int main() { soci::session database( "sqlite3",":memory:" ); database << table; database << hank; database << bill; database << fred; soci::statement statement = make_statement( database ); bind_statement( statement,2 ); execute_statement( statement ); }
更新2:当我找到cppdb library时,我最终放弃了SOCI.与SOCI不同,它只是一个非常薄的本地C API包装器,适合我的需求.
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