Computer program characterized in that it comprises instructions for implementing a pre-compiler when they are executed by a processor, said pre-compiler being designed for: - analyzing a source code, called main code, written in COBOL language and comprising: o defining a first variable, referred to as main variable, defined in the main code to contain a string of characters, and o defining a second variable, called an indicator variable, defined in the main code containing an integer number N indicating the number of first characters contained in the main variable associated with it to be used by the database; o at least one embedded SQL instruction, intended for an SQL database and capable of comprising an expression of predefined shape comprising: ▪ the main variable defined in the main code; ▪ the indicator variable relating to the main variable defined in the main code; and ▪ one or more predefined characters for associating each main variable and each indicator variable associated therewith; one or more predefined shape expressions in the embedded SQL instruction (s) being searched during this analysis; characterized in that it is further being designed for: - replacing each predefined shape expression in the embedded SQL instruction (s) found during the previous analysis by replacement code in the COBOL language providing the N first characters of the main variable when compiled by a compiler and executed by a computer, - replacing each embedded SQL expression found by COBOL replacement code. - analyzing a source code, called main code, written in COBOL language and comprising: o defining a first variable, referred to as main variable, defined in the main code to contain a string of characters, and o defining a second variable, called an indicator variable, defined in the main code containing an integer number N indicating the number of first characters contained in the main variable associated with it to be used by the database; o at least one embedded SQL instruction, intended for an SQL database and capable of comprising an expression of predefined shape comprising: ▪ the main variable defined in the main code; ▪ the indicator variable relating to the main variable defined in the main code; and ▪ one or more predefined characters for associating each main variable and each indicator variable associated therewith; o defining a first variable, referred to as main variable, defined in the main code to contain a string of characters, and o defining a second variable, called an indicator variable, defined in the main code containing an integer number N indicating the number of first characters contained in the main variable associated with it to be used by the database; o at least one embedded SQL instruction, intended for an SQL database and capable of comprising an expression of predefined shape comprising: ▪ the main variable defined in the main code; ▪ the indicator variable relating to the main variable defined in the main code; and ▪ one or more predefined characters for associating each main variable and each indicator variable associated therewith; ▪ the main variable defined in the main code; ▪ the indicator variable relating to the main variable defined in the main code; and ▪ one or more predefined characters for associating each main variable and each indicator variable associated therewith; one or more predefined shape expressions in the embedded SQL instruction (s) being searched during this analysis; characterized in that it is further being designed for: - replacing each predefined shape expression in the embedded SQL instruction (s) found during the previous analysis by replacement code in the COBOL language providing the N first characters of the main variable when compiled by a compiler and executed by a computer, - replacing each embedded SQL expression found by COBOL replacement code.