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jd-foster merged 4 commits into from
Mar 27, 2026
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simplified data type table #385

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simplified data type table
alexthrelkeld Apr 2, 2025
a5ce09a
improve descriptions in epsiode 1 data types table, added data type q…
alexthrelkeld Apr 2, 2025
82d4618
Validation and clean-up
jd-foster Mar 23, 2026
9b7acc5
Final fixes with references
jd-foster Mar 24, 2026
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82 changes: 26 additions & 56 deletions episodes/00-sql-introduction.md
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Expand Up @@ -201,28 +201,28 @@ follow these instructions:
10. In the center panel of the window that appears, set the data types for each field using the suggestions in the table below (this includes fields from the `plots` and `species` tables also).
11. Finally, click **OK** one more time to confirm the operation. Then click the **Write Changes** button to save the database.

| Field | Data Type | Motivation | Table(s) |
| ----------------------------------------------------- | :------------------------------------------------------------------------------------------------------- | ----------------------------------------------------------------------- | ---------------- |
| day | INTEGER | Having data as numeric allows for meaningful arithmetic and comparisons | surveys |
| genus | TEXT | Field contains text data | species |
| hindfoot\_length | REAL | Field contains measured numeric data | surveys |
| month | INTEGER | Having data as numeric allows for meaningful arithmetic and comparisons | surveys |
| plot\_id | INTEGER | Field contains numeric data | plots, surveys |
| plot\_type | TEXT | Field contains text data | plots |
| record\_id | INTEGER | Field contains numeric data | surveys |
| sex | TEXT | Field contains text data | surveys |
| species\_id | TEXT | Field contains text data | species, surveys |
| species | TEXT | Field contains text data | species |
| taxa | TEXT | Field contains text data | species |
| weight | REAL | Field contains measured numerical data | surveys |
| year | INTEGER | Allows for meaningful arithmetic and comparisons | surveys |
| Field | Data Type | Motivation | Table(s) |
| ----------------------------------------------------- | :----------------------- | ----------------------------------------------------------------------- | ---------------- |
| day | INTEGER | Having data as numeric allows for meaningful arithmetic and comparisons | surveys |
| genus | TEXT | Field contains text data | species |
| hindfoot\_length | REAL | Field contains measured numeric data | surveys |
| month | INTEGER | Having data as numeric allows for meaningful arithmetic and comparisons | surveys |
| plot\_id | INTEGER | Field contains numeric data | plots, surveys |
| plot\_type | TEXT | Field contains text data | plots |
| record\_id | INTEGER | Field contains numeric data | surveys |
| sex | TEXT | Field contains text data | surveys |
| species\_id | TEXT | Field contains text data | species, surveys |
| species | TEXT | Field contains text data | species |
| taxa | TEXT | Field contains text data | species |
| weight | REAL | Field contains measured numerical data | surveys |
| year | INTEGER | Allows for meaningful arithmetic and comparisons | surveys |

::::::::::::::::::::::::::::::::::::::: challenge

### Challenge

- Import the `plots` and `species` tables


::::::::::::::::::::::::::::::::::::::::::::::::::

Expand All @@ -235,46 +235,16 @@ You can also use this same approach to append new fields to an existing table.

### Data types {#datatypes}

| Data type | Description |
| ----------------------------------------------------- | :------------------------------------------------------------------------------------------------------- |
| CHARACTER(n) | Character string. Fixed-length n |
| VARCHAR(n) or CHARACTER VARYING(n) | Character string. Variable length. Maximum length n |
| BINARY(n) | Binary string. Fixed-length n |
| BOOLEAN | Stores TRUE or FALSE values |
| VARBINARY(n) or BINARY VARYING(n) | Binary string. Variable length. Maximum length n |
| INTEGER(p) | Integer numerical (no decimal). |
| SMALLINT | Integer numerical (no decimal). |
| INTEGER | Integer numerical (no decimal). |
| BIGINT | Integer numerical (no decimal). |
| DECIMAL(p,s) | Exact numerical, precision p, scale s. |
| NUMERIC(p,s) | Exact numerical, precision p, scale s. (Same as DECIMAL) |
| FLOAT(p) | Approximate numerical, mantissa precision p. A floating number in base 10 exponential notation. |
| REAL | Approximate numerical |
| FLOAT | Approximate numerical |
| DOUBLE PRECISION | Approximate numerical |
| DATE | Stores year, month, and day values |
| TIME | Stores hour, minute, and second values |
| TIMESTAMP | Stores year, month, day, hour, minute, and second values |
| INTERVAL | Composed of a number of integer fields, representing a period of time, depending on the type of interval |
| ARRAY | A set-length and ordered collection of elements |
| MULTISET | A variable-length and unordered collection of elements |
| XML | Stores XML data |

### SQL Data Type Quick Reference {#datatypediffs}
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@adamancer adamancer Apr 2, 2025

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I agree that the quick reference table is a lot for the lesson but would like to retain this in learners/sql-cheat-sheet.md.

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@alexthrelkeld alexthrelkeld Apr 2, 2025

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I've moved that quick reference table to learners/sql-cheat-sheet.md, and added a column for SQLite since that is the main database platform used in this workshop.


Different databases offer different choices for the data type definition.

The following table shows some of the common names of data types between the various database platforms:

| Data type | Access | SQLServer | Oracle | MySQL | PostgreSQL |
| :---------------------------------------------------- | :------------------------------------------------------------------------------------------------------- | :---------------------------------------------------------------------- | :--------------- | :------------ | :------------ |
| boolean | Yes/No | Bit | Byte | N/A | Boolean |
| integer | Number (integer) | Int | Number | Int / Integer | Int / Integer |
| float | Number (single) | Float / Real | Number | Float | Numeric |
| currency | Currency | Money | N/A | N/A | Money |
| string (fixed) | N/A | Char | Char | Char | Char |
| string (variable) | Text (\<256) / Memo (65k+) | Varchar | Varchar2 | Varchar | Varchar |
| binary object OLE Object Memo Binary (fixed up to 8K) | Varbinary (\<8K) | Image (\<2GB) Long | Raw Blob | Text Binary | Varbinary |
SQLite has four data types, shown in the table below.

| Data type | Description |
| ------------------ | :-------------------------------------------------------------------------------------------------------------------- |
| TEXT | Text string |
| INTEGER | Integer (positive or negative whole number) |
| REAL | Approximate numerical value (floating point number) |
| BLOB | General data with no specfic type, stored in the database exactly as given (stands for _Binary Large OBject_) |

In addition to these four data types, SQLite has a NULL value for missing data. We will talk more about dealing with missing data in Episode 3.

:::::::::::::::::::::::::::::::::::::::: keypoints

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