1=1是壹個條件為真的值,後面跟要查詢的條件。如果是倍數的話,會是和數倍以上。
比如這是我之前寫的壹段話。
string SQL = " select * from book where 1 = 1;
如果(bookID!=0)
sql=sql+"和bookID = "+bookID;
如果(!bookName.equals(" ")
sql=sql+"和bookName like“%”+bookName+“%”;
如果(!author.equals(" ")
sql=sql+"和author like“%”+author+“%”;
如果(bookStatus!=2)
sql = sql +"和status = "+book status;