Java Operations Database statement a simple error point

Let's start by looking at the following statement

String sqlstring= "SELECT * from Petmessage where petname= '" +pet.getpetname () + "';";

The above statement selects all information from the specified information where a "" is added to the left and right of the Pet.getpetname (), and the two quotation marks serve as the function of the connection string but look closely at the left and right of the quotation mark. It is the single quotation mark that is used to enclose the information in the Pet.getpetname () to keep the syntax of the SQL statement accurate!

Java Operations Database statement a simple error point