Need Database Oracle Apex expert to help with problem when comparing 2 tables

We are building web application using Oracle Apex for making reports. We have interactive report that is generated by comparing 2 tables. Each tables has Columns: Date (22 April 2016) for example Tag_id Number Table 1: contains History of the changes of Column: Number and writes on which date the column: Number was changed Table 2 : Also has column: Number and column: Date (column: Date which shows different values for column: Number for the different dates of the month) The Report is being generated when comparing columns "Tag_id" between table 1 and table 2 so we know which value from column: number for table 1 is referring to column: number in table 2. (...where table1.tag_id=table2.tag_id) Table 2 contains data in column: number for every day of the month, and Table 1 contains data that is changed in column: number once every 1,2,3 or more days. We want the report to show the values from column: Number from Table 1 and to show the values from column: Number from Table 2 while making comparison between table 1 and table 2 by column: Date The problem is when in Table 1 there is no date in column:Date which is equal to date in column:Date in Table 2, the Database doesnt know which value for column:Number to return in the Generated Report. What we want to achieve: When there is no date match in the columns:Date between Table 1 and Table 2 we want in the Generated report Apex to return the value from column:Number from Table 2 for the Date for which there is no match* and the value of column:Number from Table 1 for the closest previous date Screen Shot Table Example: [login to view URL] We need someone that knows how to solve the problem and explain to our programmer or me, how The check can be done so everything works like on my screenshot example [login to view URL] Should we use PLSQL or it can be done with JUST SQL query and how ? Or this could be done by using a some kind of procedure or the problem can be solved in some other way HOW ? Please bid on this project if you are certain that you know how to solve the problem and you have experience in Oracle Apex.