diff --git a/db_schema.sql b/db_schema.sql
index dfb9e0e..153b9dd 100644
--- a/db_schema.sql
+++ b/db_schema.sql
@@ -3,12 +3,12 @@
 -- Create SUB table
 CREATE TABLE sub (
     adsh        CHAR(20) PRIMARY KEY NOT NULL, -- Accession number, primary key
-    cik         BIGINT NOT NULL,                -- Central Index Key (CIK)
-    name        VARCHAR(150) NOT NULL,          -- Name of registrant
+    cik         BIGINT ,                -- Central Index Key (CIK)
+    name        VARCHAR(150) ,          -- Name of registrant
     sic         INTEGER,                        -- Standard Industrial Classification (SIC)
-    countryba   CHAR(2) NOT NULL,               -- Country of business address (ISO 3166-1)
+    countryba   CHAR(2) ,               -- Country of business address (ISO 3166-1)
     stprba      CHAR(2),                        -- State/Province of business address (if applicable)
-    cityba      VARCHAR(30) NOT NULL,           -- City of business address
+    cityba      VARCHAR(30) ,           -- City of business address
     zipba       VARCHAR(10),                    -- Zip code of business address
     bas1        VARCHAR(40),                    -- First line of business address
     bas2        VARCHAR(40),                    -- Second line of business address
@@ -25,18 +25,18 @@ CREATE TABLE sub (
     former      VARCHAR(150),                   -- Most recent former name
     changed     CHAR(8),                        -- Date of change from former name
     afs         CHAR(5),                        -- Filer Status with SEC
-    wksi        BOOLEAN NOT NULL,               -- Well Known Seasoned Issuer (WKSI)
-    fye         CHAR(4) NOT NULL,               -- Fiscal Year End Date (format: mmdd)
-    form        VARCHAR(10) NOT NULL,           -- Submission type (Form)
-    period      CHAR(8) NOT NULL,               -- Balance Sheet Date (format: yyyymmdd)
-    fy          INTEGER NOT NULL,               -- Fiscal Year focus (Year)
-    fp          CHAR(2) NOT NULL,               -- Fiscal Period focus (e.g., FY, Q1)
-    filed       CHAR(8) NOT NULL,               -- Date of filing (format: yyyymmdd)
-    accepted    TIMESTAMP NOT NULL,             -- Acceptance date and time by SEC
-    prevrpt     BOOLEAN NOT NULL,               -- Indicates if the submission was amended
-    detail      BOOLEAN NOT NULL,               -- Indicates detail in footnotes and schedules
-    instance    VARCHAR(32) NOT NULL,           -- Name of submitted XBRL Instance Document
-    nciks       INTEGER NOT NULL,               -- Number of CIKs included in submission
+    wksi        BOOLEAN ,               -- Well Known Seasoned Issuer (WKSI)
+    fye         CHAR(4) ,               -- Fiscal Year End Date (format: mmdd)
+    form        VARCHAR(10) ,           -- Submission type (Form)
+    period      CHAR(8) ,               -- Balance Sheet Date (format: yyyymmdd)
+    fy          INTEGER ,               -- Fiscal Year focus (Year)
+    fp          CHAR(2) ,               -- Fiscal Period focus (e.g., FY, Q1)
+    filed       CHAR(8) ,               -- Date of filing (format: yyyymmdd)
+    accepted    TIMESTAMP ,             -- Acceptance date and time by SEC
+    prevrpt     BOOLEAN ,               -- Indicates if the submission was amended
+    detail      BOOLEAN ,               -- Indicates detail in footnotes and schedules
+    instance    VARCHAR(32) ,           -- Name of submitted XBRL Instance Document
+    nciks       INTEGER ,               -- Number of CIKs included in submission
     aciks       VARCHAR(120)                    -- Additional CIKs included in submission
 );
 
@@ -44,8 +44,8 @@ CREATE TABLE sub (
 CREATE TABLE tag (
     tag         VARCHAR(256)   NOT NULL,   -- Unique identifier for a tag
     version     CHAR(20)       NOT NULL,   -- Taxonomy version if standard, else adsh
-    custom      BOOLEAN        NOT NULL,   -- 1 if custom tag, 0 if standard tag
-    abstract    BOOLEAN        NOT NULL,   -- 1 if abstract (not numeric), 0 if numeric
+    custom      BOOLEAN        ,   -- 1 if custom tag, 0 if standard tag
+    abstract    BOOLEAN        ,   -- 1 if abstract (not numeric), 0 if numeric
     datatype    VARCHAR(20),               -- Data type (if numeric)
     iord        CHAR(1),   -- "I" for point-in-time, "D" for duration
     crdr        CHAR(1),                   -- Credit/ Debit nature, if monetary
@@ -77,12 +77,12 @@ CREATE TABLE pre (
     adsh        CHAR(20)       NOT NULL,   -- Accession number
     report      INTEGER        NOT NULL,   -- Sequence number of report
     line        INTEGER        NOT NULL,   -- Sequence number of line in the report
-    stmt        CHAR(2)        NOT NULL,   -- Statement type (BS, IS, CF, EQ, CI, etc.)
-    inpth       BOOLEAN        NOT NULL,   -- Presented parenthetically or not
-    rfile       CHAR(1)        NOT NULL,   -- File type ("H" or "X")
+    stmt        CHAR(2)        ,   -- Statement type (BS, IS, CF, EQ, CI, etc.)
+    inpth       BOOLEAN        ,   -- Presented parenthetically or not
+    rfile       CHAR(1)        ,   -- File type ("H" or "X")
     tag         VARCHAR(256)   NOT NULL,   -- Tag name
     version     CHAR(20)       NOT NULL,   -- Taxonomy version
-    plabel      VARCHAR(512)   NOT NULL,   -- Preferred label for presentation
+    plabel      VARCHAR(512)   ,   -- Preferred label for presentation
 
     PRIMARY KEY (adsh, report, line),
     FOREIGN KEY (adsh) REFERENCES sub(adsh),