DBExec

Database interface function.

    
    
    
DBExec(sql)

Examples

• Supports in-memory databases. For the parameter of the DBExec function, if the sql statement begins with :, the operation is executed in the in-memory database; since there is no need to write to a file, it is faster. This approach is suitable for database operations that do not require persistent storage, for example:

  • javascript
  • python
  • rust
  • cpp

  
      javascript
      
      
  function main() {
      var strSql = [
          ":CREATE TABLE TEST_TABLE(",
          "TS INT PRIMARY KEY NOT NULL,",
          "HIGH REAL NOT NULL,",
          "OPEN REAL NOT NULL,",
          "LOW REAL NOT NULL,",
          "CLOSE REAL NOT NULL,",
          "VOLUME REAL NOT NULL)"
      ].join("")
      var ret = DBExec(strSql)
      Log(ret)
  
      // Add a record
      Log(DBExec(":INSERT INTO TEST_TABLE (TS, HIGH, OPEN, LOW, CLOSE, VOLUME) VALUES (1518970320000, 100, 99.1, 90, 100, 12345.6);"))
  
      // Query data
      Log(DBExec(":SELECT * FROM TEST_TABLE;"))
  }
  

  
      python
      
      
  def main():
      arr = [
          ":CREATE TABLE TEST_TABLE(",
          "TS INT PRIMARY KEY NOT NULL,",
          "HIGH REAL NOT NULL,",
          "OPEN REAL NOT NULL,",
          "LOW REAL NOT NULL,",
          "CLOSE REAL NOT NULL,",
          "VOLUME REAL NOT NULL)"
      ]
      strSql = ""
      for i in range(len(arr)):
          strSql += arr[i]
      ret = DBExec(strSql)
      Log(ret)
  
      # Add a record
      Log(DBExec(":INSERT INTO TEST_TABLE (TS, HIGH, OPEN, LOW, CLOSE, VOLUME) VALUES (1518970320000, 100, 99.1, 90, 100, 12345.6);"))
  
      # Query data
      Log(DBExec(":SELECT * FROM TEST_TABLE;"))
  

  
      rust
      
      
  fn main() {
      let arr = [
          ":CREATE TABLE TEST_TABLE(",
          "TS INT PRIMARY KEY NOT NULL,",
          "HIGH REAL NOT NULL,",
          "OPEN REAL NOT NULL,",
          "LOW REAL NOT NULL,",
          "CLOSE REAL NOT NULL,",
          "VOLUME REAL NOT NULL)",
      ];
      let strSql = arr.join("");
      let ret = DBExec(&strSql);
      Log!(format!("{:?}", ret));
  
      // Add a record
      Log!(format!("{:?}", DBExec(":INSERT INTO TEST_TABLE (TS, HIGH, OPEN, LOW, CLOSE, VOLUME) VALUES (1518970320000, 100, 99.1, 90, 100, 12345.6);")));
  
      // Query data
      Log!(format!("{:?}", DBExec(":SELECT * FROM TEST_TABLE;")));
  }
  

  
      c++
      
      
  void main() {
      string strSql = ":CREATE TABLE TEST_TABLE(\
          TS INT PRIMARY KEY NOT NULL,\
          HIGH REAL NOT NULL,\
          OPEN REAL NOT NULL,\
          LOW REAL NOT NULL,\
          CLOSE REAL NOT NULL,\
          VOLUME REAL NOT NULL)";
      auto ret = DBExec(strSql);
      Log(ret);
  
      // Add a record
      Log(DBExec(":INSERT INTO TEST_TABLE (TS, HIGH, OPEN, LOW, CLOSE, VOLUME) VALUES (1518970320000, 100, 99.1, 90, 100, 12345.6);"));
  
      // Query data
      Log(DBExec(":SELECT * FROM TEST_TABLE;"));
  }
  

• Use the DBExec() function to create a data table.

  • javascript
  • python
  • rust
  • cpp

  
      javascript
      
      
  function main() {
      var strSql = [
          "CREATE TABLE TEST_TABLE(",
          "TS INT PRIMARY KEY NOT NULL,",
          "HIGH REAL NOT NULL,",
          "OPEN REAL NOT NULL,",
          "LOW REAL NOT NULL,",
          "CLOSE REAL NOT NULL,",
          "VOLUME REAL NOT NULL)"
      ].join("")
      var ret = DBExec(strSql)
      Log(ret)
  }
  

  
      python
      
      
  def main():
      arr = [
          "CREATE TABLE TEST_TABLE(",
          "TS INT PRIMARY KEY NOT NULL,",
          "HIGH REAL NOT NULL,",
          "OPEN REAL NOT NULL,",
          "LOW REAL NOT NULL,",
          "CLOSE REAL NOT NULL,",
          "VOLUME REAL NOT NULL)"
      ]
      strSql = ""
      for i in range(len(arr)):
          strSql += arr[i]
      ret = DBExec(strSql)
      Log(ret)
  

  
      rust
      
      
  fn main() {
      let arr = [
          "CREATE TABLE TEST_TABLE(",
          "TS INT PRIMARY KEY NOT NULL,",
          "HIGH REAL NOT NULL,",
          "OPEN REAL NOT NULL,",
          "LOW REAL NOT NULL,",
          "CLOSE REAL NOT NULL,",
          "VOLUME REAL NOT NULL)",
      ];
      let strSql = arr.join("");
      let ret = DBExec(&strSql);
      Log!(format!("{:?}", ret));
  }
  

  
      c++
      
      
  void main() {
      string strSql = "CREATE TABLE TEST_TABLE(\
          TS INT PRIMARY KEY NOT NULL,\
          HIGH REAL NOT NULL,\
          OPEN REAL NOT NULL,\
          LOW REAL NOT NULL,\
          CLOSE REAL NOT NULL,\
          VOLUME REAL NOT NULL)";
      auto ret = DBExec(strSql);
      Log(ret);
  }
  

• Perform insert, delete, query, and update operations on records in a data table.

  • javascript
  • python
  • rust
  • cpp

  
      javascript
      
      
  function main() {
      var strSql = [
          "CREATE TABLE TEST_TABLE(",
          "TS INT PRIMARY KEY NOT NULL,",
          "HIGH REAL NOT NULL,",
          "OPEN REAL NOT NULL,",
          "LOW REAL NOT NULL,",
          "CLOSE REAL NOT NULL,",
          "VOLUME REAL NOT NULL)"
      ].join("")
      Log(DBExec(strSql))
  
      // Insert a record
      Log(DBExec("INSERT INTO TEST_TABLE (TS, HIGH, OPEN, LOW, CLOSE, VOLUME) VALUES (1518970320000, 100, 99.1, 90, 100, 12345.6);"))
  
      // Query data
      Log(DBExec("SELECT * FROM TEST_TABLE;"))
  
      // Update data
      Log(DBExec("UPDATE TEST_TABLE SET HIGH=? WHERE TS=?", 110, 1518970320000))
  
      // Delete data
      Log(DBExec("DELETE FROM TEST_TABLE WHERE HIGH=?", 110))
  }
  

  
      python
      
      
  def main():
      arr = [
          "CREATE TABLE TEST_TABLE(",
          "TS INT PRIMARY KEY NOT NULL,",
          "HIGH REAL NOT NULL,",
          "OPEN REAL NOT NULL,",
          "LOW REAL NOT NULL,",
          "CLOSE REAL NOT NULL,",
          "VOLUME REAL NOT NULL)"
      ]
      strSql = ""
      for i in range(len(arr)):
          strSql += arr[i]
      Log(DBExec(strSql))
  
      # Insert a record
      Log(DBExec("INSERT INTO TEST_TABLE (TS, HIGH, OPEN, LOW, CLOSE, VOLUME) VALUES (1518970320000, 100, 99.1, 90, 100, 12345.6);"))
  
      # Query data
      Log(DBExec("SELECT * FROM TEST_TABLE;"))
  
      # Update data
      Log(DBExec("UPDATE TEST_TABLE SET HIGH=? WHERE TS=?", 110, 1518970320000))
  
      # Delete data
      Log(DBExec("DELETE FROM TEST_TABLE WHERE HIGH=?", 110))
  

  
      rust
      
      
  fn main() {
      let arr = [
          "CREATE TABLE TEST_TABLE(",
          "TS INT PRIMARY KEY NOT NULL,",
          "HIGH REAL NOT NULL,",
          "OPEN REAL NOT NULL,",
          "LOW REAL NOT NULL,",
          "CLOSE REAL NOT NULL,",
          "VOLUME REAL NOT NULL)",
      ];
      let strSql = arr.join("");
      Log!(format!("{:?}", DBExec(&strSql)));
  
      // Insert a record
      Log!(format!("{:?}", DBExec("INSERT INTO TEST_TABLE (TS, HIGH, OPEN, LOW, CLOSE, VOLUME) VALUES (1518970320000, 100, 99.1, 90, 100, 12345.6);")));
  
      // Query data
      Log!(format!("{:?}", DBExec("SELECT * FROM TEST_TABLE;")));
  
      // Update data. Rust's DBExec() function only accepts a single SQL statement string argument and does not support the ? placeholder for passing parameters; parameter values are written directly in the statement
      Log!(format!("{:?}", DBExec("UPDATE TEST_TABLE SET HIGH=110 WHERE TS=1518970320000;")));
  
      // Delete data
      Log!(format!("{:?}", DBExec("DELETE FROM TEST_TABLE WHERE HIGH=110;")));
  }
  

  
      c++
      
      
  void main() {
      string strSql = "CREATE TABLE TEST_TABLE(\
          TS INT PRIMARY KEY NOT NULL,\
          HIGH REAL NOT NULL,\
          OPEN REAL NOT NULL,\
          LOW REAL NOT NULL,\
          CLOSE REAL NOT NULL,\
          VOLUME REAL NOT NULL)";
      Log(DBExec(strSql));
  
      // Insert a record
      Log(DBExec("INSERT INTO TEST_TABLE (TS, HIGH, OPEN, LOW, CLOSE, VOLUME) VALUES (1518970320000, 100, 99.1, 90, 100, 12345.6);"));
  
      // Query data
      Log(DBExec("SELECT * FROM TEST_TABLE;"));
  
      // Update data
      Log(DBExec("UPDATE TEST_TABLE SET HIGH=? WHERE TS=?", 110, 1518970320000));
  
      // Delete data
      Log(DBExec("DELETE FROM TEST_TABLE WHERE HIGH=?", 110));
  }
  

Returns

Arguments

See Also

Remarks

• By passing an argument to the DBExec() function, you can operate on the live trading database (SQLite database).

  • It supports insert, delete, query, and update operations on data in the live trading database, and supports SQLite syntax.

  • The system-reserved tables in the live trading database include: kvdb, cfg, log, profit, chart. Please do not operate on these tables.

  • Transactions are currently not supported, and such operations are not recommended, as they may cause system conflicts.

  • The DBExec() function only supports live trading.