database

GoLang: Inserting records into Oracle Database using goracle

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In this blog post I’ll give some examples of how to process data for inserting into a table in an Oracle Database. I’ve had some previous blog posts on how to setup and connecting to an Oracle Database, and another on retrieving data from an Oracle Database and the importance of setting the Array Fetch Size.

When manipulating data the statements can be grouped (generally) into creating new data and updating existing data.

When working with this kind of processing we need to avoid the creation of the statements as a concatenation of strings. This opens the possibility of SQL injection, plus we are not allowing the optimizer in the database to do it’s thing. Prepared statements allows for the reuse of execution plans and this in turn can speed up our data processing and applications.

In a previous blog post I gave a simple example of a prepared statement for querying data and then using it to pass in different values as a parameter to this statement.

dbQuery, err := db.Prepare("select cust_first_name, cust_last_name, cust_city from sh.customers where cust_gender = :1")  
if err != nil {
    fmt.Println(err) 
    return  
}  
defer dbQuery.Close() 

rows, err := dbQuery.Query('M')  
if err != nil { 
    fmt.Println(".....Error processing query") 
    fmt.Println(err) 
    return  
}  
defer rows.Close()  

var CustFname, CustSname,CustCity string 
for rows.Next() {  
    rows.Scan(&CustFname, &CustSname, &CustCity) 
    fmt.Println(CustFname, CustSname, CustCity)  
}

For prepared statements for inserting data we can follow a similar structure. In the following example a table call LAST_CONTACT is used. This table has columns:

  • CUST_ID
  • CON_METHOD
  • CON_MESSAGE
_, err := db.Exec("insert into LAST_CONTACT(cust_id, con_method, con_message) VALUES(:1, :2, :3)", 1, "Phone", "First contact with customer")
if err != nil {
    fmt.Println(".....Error Inserting data") 
    fmt.Println(err) 
    return
}

an alternative is the following and allows us to get some additional information about what was done and the result from it. In this example we can get the number records processed.

stmt, err := db.Prepare("insert into LAST_CONTACT(cust_id, con_method, con_message) VALUES(:1, :2, :3)") 
if err != nil { 
    fmt.Println(err) 
    return 
}

res, err := dbQuery.Query(1, "Phone", "First contact with customer")  
if err != nil { 
    fmt.Println(".....Error Inserting data") 
    fmt.Println(err) 
    return  
} 

rowCnt := res.RowsAffected()
fmt.Println(rowCnt, " rows inserted.")

A similar approach can be taken for updating and deleting records

Managing Transactions

With transaction, a number of statements needs to be processed as a unit. For example, in double entry book keeping we have two inserts. One Credit insert and one debit insert. To do this we can define the start of a transaction using db.Begin() and the end of the transaction with a Commit(). Here is an example were we insert two contact details.

// start the transaction
transx, err := db.Begin()
if err != nil {
    fmt.Println(err) 
    return  
}

// Insert first record
_, err := db.Exec("insert into LAST_CONTACT(cust_id, con_method, con_message) VALUES(:1, :2, :3)", 1, "Email", "First Email with customer") 
if err != nil { 
    fmt.Println(".....Error Inserting data - first statement") 
    fmt.Println(err) 
    return 
}
// Insert second record
_, err := db.Exec("insert into LAST_CONTACT(cust_id, con_method, con_message) VALUES(:1, :2, :3)", 1, "In-Person", "First In-Person with customer") 
if err != nil { 
    fmt.Println(".....Error Inserting data - second statement") 
    fmt.Println(err) 
    return 
}

// complete the transaction
err = transx.Commit()
if err != nil {
    fmt.Println(".....Error Committing Transaction") 
    fmt.Println(err) 
    return 
}

 

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GoLang: Querying records from Oracle Database using goracle

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Continuing my series of blog posts on using Go Lang with Oracle, in this blog I’ll look at how to setup a query, run the query and parse the query results. I’ll give some examples that include setting up the query as a prepared statement and how to run a query and retrieve the first record returned. Another version of this last example is a query that returns one row.

Check out my previous post on how to create a connection to an Oracle Database.

Let’s start with a simple example. This is the same example from the blog I’ve linked to above, with the Database connection code omitted.

    dbQuery := "select table_name from user_tables where table_name not like 'DM$%' and table_name not like 'ODMR$%'"
    rows, err := db.Query(dbQuery)
    if err != nil {
        fmt.Println(".....Error processing query")
        fmt.Println(err)
        return
    }
    defer rows.Close()

    fmt.Println("... Parsing query results") 
    var tableName string
    for rows.Next() {
        rows.Scan(&tableName)
        fmt.Println(tableName)
    }

Processing a query and it’s results involves a number of steps and these are:

  1. Using Query() function to send the query to the database. You could check for errors when processing each row
  2. Iterate over the rows using Next()
  3. Read the columns for each row into variables using Scan(). These need to be defined because Go is strongly typed.
  4. Close the query results using Close(). You might want to defer the use of this function but depends if the query will be reused. The result set will auto close the query after it reaches the last records (in the loop). The Close() is there just in case there is an error and cleanup is needed.

You should never use * as a wildcard in your queries. Always explicitly list the attributes you want returned and only list the attributes you want/need. Never list all attributes unless you are going to use all of them. There can be major query performance benefits with doing this.

Now let us have a look at using prepared statement. With these we can parameterize the query giving us greater flexibility and reuse of the statements. Additionally, these give use better query execution and performance when run the the database as the execution plans can be reused.

    dbQuery, err := db.Prepare("select cust_first_name, cust_last_name, cust_city from sh.customers where cust_gender = :1")
    if err != nil {
        fmt.Println(err) 
        return
    }
    defer dbQuery.Close()

    rows, err := dbQuery.Query('M')
    if err != nil {
        fmt.Println(".....Error processing query") 
        fmt.Println(err) 
        return
    }
    defer rows.Close()

    var CustFname, CustSname,CustCity string
    for rows.Next() {
        rows.Scan(&CustFname, &CustSname, &CustCity)   
        fmt.Println(CustFname, CustSname, CustCity) 
    }

Sometimes you may have queries that return only one row or you only want the first row returned by the query. In cases like this you can reduce the code to something like the following.

var CustFname, CustSname,CustCity string
err := db.Prepare("select cust_first_name, cust_last_name, cust_city from sh.customers where cust_gender = ?").Scan(&CustFname, &CustSname, &CustCity)  
if err != nil {
    fmt.Println(err) 
    return  
} 
fmt.Println(CustFname, CustSname, CustCity)

or an alternative to using Quer(), use QueryRow()

dbQuery, err := db.Prepare("select cust_first_name, cust_last_name, cust_city from sh.customers where cust_gender = ?")  
if err != nil {
    fmt.Println(err) 
    return  
}  
defer dbQuery.Close() 

var CustFname, CustSname,CustCity string
err := dbQuery.QueryRow('M').Scan(&CustFname, &CustSname, &CustCity)  
if err != nil { 
    fmt.Println(".....Error processing query") 
    fmt.Println(err) 
    return  
}  
fmt.Println(CustFname, CustSname, CustCity)

 

 

 

 

18c is now available (but only on the Cloud)

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On Friday afternoon (16th February) we started to see tweets and blog posts from people in Oracle saying that Oracle 18c was now available. But is only available on Oracle Cloud and Engineered Systems.

It looks like we will have to wait until the Autumn before we can install it ourselves on our own servers 😦

Here is the link to the official announcement for Oracle 18c.

Oracle 18c is really Oracle 12.2.0.2. The next full new release of the Oracle database is expected to be Oracle 19.

The new features and incremental enhancements in Oracle 18c are:

  • Multitenant
  • In-Memory
  • Sharding
  • Memory Optimized Fetches
  • Exadata RAC Optimizations
  • High Availability
  • Security
  • Online Partition Merge
  • Improved Machine Learning (OAA)
  • Polymorphic Table Functions
  • Spatial and Graph
  • More JSON improvements
  • Private Temporary Tablespaces
  • New mode for Connection Manager

And now the all important links to the documentation.

Oracle 18c Documentation

Oracle 18c New Features

Oracle 18c Data Warehousing

To give Oracle 18c a try you will need to go to cloud.oracle.com and select Database from the drop down list from the Platform menu. Yes you are going to need an Oracle Cloud account and some money or some free credit. Go and get some free cloud credits at the upcoming Oracle Code events.

If you want a ‘free’ way of trying out Oracle 18c, you can use Oracle Live SQL. They have setup some examples of the new features for you to try.

NewImage

NOTE: Oracle 18c is not Autonomous. Check out Tim Hall’s blog posts about this. The Autonomous Oracle Database is something different, and we will be hearing more about this going forward.

12.2 DBaaS (Extreme Edition) possible bug/issue with the DB install/setup

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A few weeks ago the 12.2 Oracle Database was released on the cloud. I immediately set an account and got my 12.2 DBaaS setup. This was a relatively painless process and quick.

For me I wanted to test out all the new Oracle Advanced Analytics new features and the new features in SQL Developer 4.2 that only become visible when you are using the 12.2 Database.

When you are go to use the Oracle Data Miner (GUI tool) in SQL Developer 4.2, it will check to see if the ODMr repository is installed in the database. If it isn’t then you will be promoted for the SYS password.

This is the problem. In previous version of the DBaaS (12.1, etc) this was not an issue.

When you go to create your DBaaS you are asked for a password that will be used for the admin accounts of the database.

But when I entered the password for SYS, I got an error saying invalid password.

After using ssh to create a terminal connection to the DBaaS I was able to to connect to the container using

sqlplus / as sysdba

and also using

sqlplus sys/ as sysdba

Those worked fine. But when I tried to connect to the PDB1 I got the invalid username and/or password error.

sqlplus sys/@pdb1 as sysdba

I reconnected as follows

sqlplus / as sysdba

and then changed the password for SYS with containers=all

This command completed without errors but when I tried using the new password to connect the the PDB1 I got the same error.

After 2 weeks working with Oracle Support they eventually pointed me to the issue of the password file for the PDB1 was missing. They claim this is due to an error when I was creating/installing the database.

But this was a DBaaS and I didn’t install the database. This is a problem with how Oracle have configured the installation.

The answer was to create a password file for the PDB1 using the following

% orapwd file=$ORACLE_HOME/dbs/orapwPDB1 password= entries=10

I then changed the password again for SYS, then tried to connect as SYS to the PDB1, and if by magic I was connected.

I then tried installing the ODMr repository again (in SQL Developer) and when I entered the new password for SYS, it worked !

It's a pity that it took Oracle Support 2 weeks to get me to this point.

As 12.2 is a cloud service hopefully Oracle will get that issue fixed soon so that one one else has to suffer like I did.

Installing Oracle 12.1.0.2 on Windows 64bit

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The following steps are what I did for installing 12.1.0.2 on Windows.

1. Download the Oracle installation ZIP files from the Oracle Downloads page.

DB Install 15

2. Unzip the two 12c downloads files into the same directory.

3. Go to the newly created directory (it is probably called ‘database’) and you will find a file called setup.exe. Double click on this file.

DB Install 1

After a couple of seconds you will see the Oracle Database 12c splash screen.

DB Install 2

4. Step 1 : Configure Security Updates : Un-tick the tick-box and click the Next button. A warning message will appear. You can click on the Yes button to proceed.

DB Install 3

5. Step 2 : Installation Options : select the Create and Configure a Database option and then click the Next button.

DB Install 4

6. Step 3 : System Class : Select the Server Class option and then click the Next button.

DB Install 5

7. Step 4 : Grid Installation Options : Select the Single Instance Database Installation option and then click the next button.

DB Install 6

8. Step 5 : Select Install Type : Select the Typical install option and then click the Next button.

DB Install 7

9. Step 6 : Oracle Home User Selection : Select the Use Windows Built-in Account option and then click the Next button. A warning message appears. Click the Yes button.

DB Install 8

10. Step 7 : Typical Install Configuration : Set Global Database Name to cdb12c for the container database name. Set the Administrative password for the container database. Set the name of the pluggable database that will be created. Set this to pdb12c. Or you can accept the default names. Then click the Next button. If you get a warning message saying the password does not conform to the recommended standards, you can click the Yes button to ignore this warning and proceed.

DB Install 9

11. Step 8 : Prerequisite Checks : the install will check to see that you have enough space and necessary permissions etc.

12. Step 9 : Summary : When the prerequisite checks (like checking you have enough space and privileges) are finished you will get a window like the following.

DB Install 10

13. Step 10 : Install : You are now ready to start the install process. To do this click on the Install button in the Summary screen.

DB Install 11

You can now sit back, relax and watch the installation of 12.1.0.2c (with the in-memory option) complete.

You may get some Windows Security Alert windows pop up. Just click on the Allow Access button.

Then the Database Configuration Assistant will start. This step might take a while to complete.

DB Install 12

When everything is done you will get something like the following.

DB Install 13

Congratulations you now have Oracle Database 12.1.0.2c installed.

But you are not finished yet!!!

14. Add entry to TNSNAMES.ORA : you will need to add an entry to your tnsnames.ora file for the pluggable database. There is be an entry for the container DB but not for the pluggable. Here is what I added to my tnsnames.ora.

DB Install 14

The last step you need to do is to tell the container database to start up the pluggables when you reboot the server/laptop/PC/VM. To do this you will need to create the following trigger in the container DB.

sqlplus / as sysdba

CREATE or REPLACE trigger OPEN_ALL_PLUGGABLES

    after startup

    on database

BEGIN

    execute immediate ‘alter pluggable database all open’;

END open_all_pdbs;

Restart your database or machine and you plug gage DB ‘pdb12c’ will no automatically start.

You are all finished now 🙂

Enjoy 🙂

Oracle Advanced Analytics and Oracle Fusion Apps

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At a recent Oracle User Group conference, I was part of a round table discussion on Apps and BI. Unfortunately most of the questions were focused on Apps and the new Fusion Applications from Oracle. I mentioned that there was data mining functionality (using the Oracle Advanced Analytics Option) built into the Fusion Apps, it seems to come as a surprise to the Apps people. They were not aware of this built in functionality and capabilities. Well Oracle Data Mining and Oracle Advanced Analytics has been built into the following Oracle Fusion Applications.

  • Oracle Fusion HCM Workforce Predictions
  • Oracle Fusion CRM Sales Prediction Engine
  • Oracle Spend Classification
  • Oracle Sales Prospector
  • Oracle Adaptive Access Manager

Oracle Data Mining and Oracle Advanced Applications are also being used in the following applications:

  • Oracle Airline Data Model
  • Oracle Communications Data Model
  • Oracle Retail Data Model
  • Oracle Security Governor for Healthcare

I intend to submit a presentation on this topic to future Oracle User Group conferences as a way of spreading the Advanced Analytics message within the Oracle user community. If you would like me to present on this topic at your conference or SIG drop me an email and we can make the necessary arrangement 🙂

Oracle 11.2g install on OLE 6.x

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This notes are really just a reminder to myself of the typical “issues” that I encounter every time I do a new install of OEL 6.x and 11.2.0.4

These notes are in addition to the excellent installation instructions given by oracle-base.com: oel install, DB 11.2.0.x install

The notes listed below are just a reminder to myself of things that I seem to always have to look up. If you finish them useful then great.

1. Display issue & Installer not able to run

install says to do xhost +:0.0 this can give an error

instead do host +:0.0 and that should allow the installer to run

2. Now enough swap space when installer checks the pre-requisites

Need to add an addition 500M to the swap space

su (and then enter the password)

dd if=/dev/zero of=/tmp/swapfile bs=1M count=500

mkswap /tmp/swapfile

swapon /tmp/swapfile

exit (to return to the oracle user)

you can then turn off the extra space (if you really need to) after the install is finished

swapoff /tmp/swapfile

rm /tmp/swapfile


3. Post-Installation task

don’t forget the final step, to set to restart flag

as root

vi /etc/oratab

change the following line to have the Y at the end (instead of the N)

DB11G:/u01/app/oracle/product/11.2.0/db_1:Y


4. Set up the automated start and stop of the DB

Again Oracle-Base gives an excellent set of instructions for doing this. Click here.