11 KiB
11 KiB
DatabasePrint
Prints a table or an SQL request execution result in the Experts journal.
long DatabasePrint(
int database, // database handle received in DatabaseOpen
const string table_or_sql, // a table or an SQL request
uint flags // combination of flags
);
Parameters
database
[in] Database handle received in DatabaseOpen().
table_or_sql
[in] A name of a table or a text of an SQL request whose results are displayed in the Experts journal.
flags
[in] Combination of flags defining the output formatting. The flags are defined as follows:
DATABASE_PRINT_NO_HEADER – do not display table column names (field names)
DATABASE_PRINT_NO_INDEX – do not display string indices
DATABASE_PRINT_NO_FRAME – do not display a frame separating a header and data
DATABASE_PRINT_STRINGS_RIGHT – align strings to the right.
If flags=0, the columns and the strings are displayed, the header and the data are separated by the frame, while the strings are aligned to the left.
Return Value
Return the number of exported strings or -1 in case of an error. To get the error code, use GetLastError(), the possible responses are:
- ERR_INTERNAL_ERROR (4001) – critical runtime error;
- ERR_NOT_ENOUGH_MEMORY (4004) - insufficient memory;
- ERR_DATABASE_INTERNAL (5120) – internal database error;
- ERR_DATABASE_INVALID_HANDLE (5121) - invalid database handle;
Note
If the journal displays request results, the SQL request should begin with "SELECT" or "select". In other words, the SQL request cannot alter the database status, otherwise DatabasePrint() fails with an error.
Example:
//+------------------------------------------------------------------+
//| Script program start function |
//+------------------------------------------------------------------+
void OnStart()
{
string filename="departments.sqlite";
//--- create or open the database in the common terminal folder
int db=DatabaseOpen(filename, DATABASE_OPEN_READWRITE | DATABASE_OPEN_CREATE |DATABASE_OPEN_COMMON);
if(db==INVALID_HANDLE)
{
Print("DB: ", filename, " open failed with code ", GetLastError());
return;
}
//--- create the COMPANY table
if(!CreataTableCompany(db))
{
DatabaseClose(db);
return;
}
//--- create the DEPARTMENT table
if(!CreataTableDepartment(db))
{
DatabaseClose(db);
return;
}
//--- display the list of all fields in the COMPANY and DEPARTMENT tables
PrintFormat("Try to print request \"PRAGMA TABLE_INFO(COMPANY);PRAGMA TABLE_INFO(DEPARTMENT)\"");
if(DatabasePrint(db, "PRAGMA TABLE_INFO(COMPANY);PRAGMA TABLE_INFO(DEPARTMENT)", 0)<0)
{
PrintFormat("DatabasePrint(\"PRAGMA TABLE_INFO()\") failed, error code=%d", GetLastError());
DatabaseClose(db);
return;
}
//--- display the COMPANY table in the log
PrintFormat("Try to print request \"SELECT * from COMPANY\"");
if(DatabasePrint(db, "SELECT * from COMPANY", 0)<0)
{
Print("DatabasePrint failed with code ", GetLastError());
DatabaseClose(db);
return;
}
//--- request text for combining the COMPANY and DEPARTMENT tables
string request="SELECT EMP_ID, NAME, DEPT FROM COMPANY LEFT OUTER JOIN DEPARTMENT "
"ON COMPANY.ID = DEPARTMENT.EMP_ID";
//--- display the table combining result
PrintFormat("Try to print request \"SELECT EMP_ID, NAME, DEPT FROM COMPANY LEFT OUTER JOIN DEPARTMENT\"");
if(DatabasePrint(db, request, 0)<0)
{
Print("DatabasePrint failed with code ", GetLastError());
DatabaseClose(db);
return;
}
//--- close the database
DatabaseClose(db);
}
/*
Conclusion:
Try to print request "PRAGMA TABLE_INFO(COMPANY);PRAGMA TABLE_INFO(DEPARTMENT)"
#| cid name type notnull dflt_value pk
-+-------------------------------------------
1| 0 ID INT 1 1
2| 1 NAME TEXT 1 0
3| 2 AGE INT 1 0
4| 3 ADDRESS CHAR(50) 0 0
5| 4 SALARY REAL 0 0
#| cid name type notnull dflt_value pk
-+------------------------------------------
1| 0 ID INT 1 1
2| 1 DEPT CHAR(50) 1 0
3| 2 EMP_ID INT 1 0
Try to print request "SELECT * from COMPANY"
#| ID NAME AGE ADDRESS SALARY
-+--------------------------------
1| 1 Paul 32 California 25000.0
2| 2 Allen 25 Texas 15000.0
3| 3 Teddy 23 Norway 20000.0
4| 4 Mark 25 Rich-Mond 65000.0
5| 5 David 27 Texas 85000.0
6| 6 Kim 22 South-Hall 45000.0
7| 7 James 24 Houston 10000.0
Try to print request "SELECT EMP_ID, NAME, DEPT FROM COMPANY LEFT OUTER JOIN DEPARTMENT"
#| EMP_ID NAME DEPT
-+-------------------------
1| 1 Paul IT Billing
2| 2 Allen Engineering
3| Teddy
4| Mark
5| David
6| Kim
7| 7 James Finance
*/
//+------------------------------------------------------------------+
//| Create the COMPANY table |
//+------------------------------------------------------------------+
bool CreateTableCompany(int database)
{
//--- if the COMPANY table exists, delete it
if(DatabaseTableExists(database, "COMPANY"))
{
//--- delete the table
if(!DatabaseExecute(database, "DROP TABLE COMPANY"))
{
Print("Failed to drop table COMPANY with code ", GetLastError());
return(false);
}
}
//--- create the COMPANY table
if(!DatabaseExecute(database, "CREATE TABLE COMPANY("
"ID INT PRIMARY KEY NOT NULL,"
"NAME TEXT NOT NULL,"
"AGE INT NOT NULL,"
"ADDRESS CHAR(50),"
"SALARY REAL );"))
{
Print("DB: create table COMPANY failed with code ", GetLastError());
return(false);
}
//--- enter data to the COMPANY table
if(!DatabaseExecute(database, "INSERT INTO COMPANY (ID,NAME,AGE,ADDRESS,SALARY) VALUES (1, 'Paul', 32, 'California', 25000.00); "
"INSERT INTO COMPANY (ID,NAME,AGE,ADDRESS,SALARY) VALUES (2, 'Allen', 25, 'Texas', 15000.00); "
"INSERT INTO COMPANY (ID,NAME,AGE,ADDRESS,SALARY) VALUES (3, 'Teddy', 23, 'Norway', 20000.00); "
"INSERT INTO COMPANY (ID,NAME,AGE,ADDRESS,SALARY) VALUES (4, 'Mark', 25, 'Rich-Mond', 65000.00); "
"INSERT INTO COMPANY (ID,NAME,AGE,ADDRESS,SALARY) VALUES (5, 'David', 27, 'Texas', 85000.0); "
"INSERT INTO COMPANY (ID,NAME,AGE,ADDRESS,SALARY) VALUES (6, 'Kim', 22, 'South-Hall', 45000.0); "
"INSERT INTO COMPANY (ID,NAME,AGE,ADDRESS,SALARY) VALUES (7, 'James', 24, 'Houston', 10000.00); "))
{
Print("COMPANY insert failed with code ", GetLastError());
return(false);
}
//--- success
return(true);
}
//+------------------------------------------------------------------+
//| Create the DEPARTMENT table |
//+------------------------------------------------------------------+
bool CreateTableDepartment(int database)
{
//--- if the DEPARTMENT table exists, delete it
if(DatabaseTableExists(database, "DEPARTMENT"))
{
//--- delete the table
if(!DatabaseExecute(database, "DROP TABLE DEPARTMENT"))
{
Print("Failed to drop table DEPARTMENT with code ", GetLastError());
return(false);
}
}
//--- create the DEPARTMENT table
if(!DatabaseExecute(database, "CREATE TABLE DEPARTMENT ("
"ID INT PRIMARY KEY NOT NULL,"
"DEPT CHAR(50) NOT NULL,"
"EMP_ID INT NOT NULL);"))
{
Print("DB: create table DEPARTMENT failed with code ", GetLastError());
return(false);
}
//--- enter data to the DEPARTMENT table
if(!DatabaseExecute(database, "INSERT INTO DEPARTMENT (ID,DEPT,EMP_ID) VALUES (1, 'IT Billing', 1); "
"INSERT INTO DEPARTMENT (ID,DEPT,EMP_ID) VALUES (2, 'Engineering', 2); "
"INSERT INTO DEPARTMENT (ID,DEPT,EMP_ID) VALUES (3, 'Finance', 7);"))
{
Print("DEPARTMENT insert failed with code ", GetLastError());
return(false);
}
//--- success
return(true);
}
//+-------------------------------------------------------------------
See also